Brevoortia pectinata.

42. The following is an exact description of Jenyns species of Bre voortia from the Atlantic coast of Paraguay and Patagonia:

Brevoortia pectinata (Jenyns) Gill. DARWIN'S MENHADEN.

Diagnosis.-Proportions of head and jaws as in B. tyrannus. Height of body almost three-eighths of total length, and greater proportionally than in B. tyrannus. Fins nearly as in B. tyrannus, but uniformly averaging slightly more; the height of the dorsal somewhat less than three twentieths of total length; that of the anal equal to or slightly less than half the length of the maxillary. The caudal fin is somewhat longer and more furcate; the length of the external rays never being less than five-sixths of the length of the head, while that of the medial rays remains proportionally the same as in the species first described. Insertion of ventral somewhat behind tip of pectoral, this fin and this dorsal being uniformly somewhat farther back than in B. tyrannus; the insertion of the latter from one to four one-hundredths posterior to a point equidistant from the snout and the base of the median caudal rays, and, as in B. tyrannus, behind the vertical from the insertion of the venhas 48m Longizere 0.20-25 intimonsonans Scales very large, considerably serrated, and arranged regularly in 18-20 transverse and 50 longitudinal rows.

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Scales forming sheath at base of pectoral not large. Operculum smooth or with inconspicuous and few striations. Squamation upon lobes of caudal extensive and conspicuous.

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Variations.

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The variations in the individual specimens studied are not of great importance, and are indicated in the tables of measurements.

43. The largest specimen on record is represented by a plaster cast in the National Museum, which is 20 inches in length. The average size of the fish upon the coast of Connecticut and Massachusetts is not far from 12 to 15 inches. The United States Menhaden Oil and Guano Association, in estimating the number of fish in a certain bulk, allow 22 cubic inches to each fish. The relation between length and weight is indicated in the following measurements, made at Noank, Conn., in 1875. These fish were all members of the same school.

44. The table given in the preceding paragraph indicates a very decided uniformity in the size of the individuals making up the same school. I have observed this uniformity in many schools, though I have not often measured many individuals from the same school. This

uniformity in length and weight is less remarkable, however, than the uniformity to be noticed in the shape and proportions of the members of the same schools. Variations are chiefly observable in the thickness and height of the body and the head and in the length of the fins, especially the pectorals and the caudal. These differences in shape are necessarily correlated with the activity and swiftness of the fish. Hence the differences in the wariness, swiftness, and difficulty in capture, so often referred to by old menhaden fishermen.

As a general rule, according to Mr. Dudley, the fall fish are mixed together without reference to fatness; the latest ones, however, which are supposed to be the main fish on their southern migration, are generally fat.

Annual rate of growth.

45. The shad is supposed to attain its full size in four years. Cap. tain Atwood believes that the mackerel requires an equal length of time in which to grow to its adult size of 17 or 18 inches. From studies made in 1856, he concluded that they grew to the length of 2 inches in about thirty days, and 4 inches in forty-five days, becoming 6 or 7 inches long before the October migration, the spawning having taken place about the middle of May. In the second year they are the "blinks;" in the third, "tinkers;" and in the fourth, full-grown mackerel. The menhaden must require three and perhaps four years to attain adult size. Those which strike in at midsummer on the coast of New England are probably hatched from the eggs spawned in the previous fall and winter. They are from 2 to 5 inches long. The second year's growth is doubtless represented by the smallest sizes of the schooling fish, measuring from 7 to 10 inches, such as are catalogued in bottles Nos. 14045, 14846, and 18049. The third year's fish would be represented by the abundant schools of fish of 12 and 14 inches, like those with measurements specified in paragraph 43. The full-grown fish are the immense ones taken in Maine and Massachusetts, measuring 16 and 18 inches.

. A most interesting circumstance is narrated by Mr. George W. Miles, to whom I am indebted for many very valuable suggestions utilized elsewhere. His observations were made in Long Island Sound. He writes: "In 1873 there were immense numbers of small fish, from 1 to 2 inches long, which appeared on the surface in the month of September. Thousands of schools could be seen at a time and great numbers in each school. They appeared to take possession of all the waters for the remainder of that season. In 1874 these fish appeared again, late in the season, and were about double the size they were in 1873. In 1875 they appeared again, much earlier, and in 1876 they came in about the first of June, having increased in size and numbers. Apparently they occupied the whole waters of the sound, so much so, that the larger fish which frequented the sound were actually crowded out of it or left for other waters, and remained off Block Island at sea the remainder of the

season, and gave up the field to be occupied by the smaller fish. The result of this abundance of small fish was a complete failure of the fishery for the two years 1875 and 1876. In 1877 we provided ourselves with smaller-meshed nets, and proceeded to catch the smaller fish, which had now attained about two-thirds the average size of fish in this locality and weighed about half a pound each. We could catch these by using nets of 23 inch mesh. About 15,000,000 of them were taken by our twelve gangs." Mr. Miles's observations seem to indicate that the period of growth sometimes, if not always, extends over a period of five or six years.

Seasonal rate of growth.

46. There is probably a much greater proportional increase in the size of individuals in the three or four months of their sojourn in northern waters than in the winter and spring. This is clearly indicated by the emaciated condition in which they make their first appearance in our waters, their winter's existence having been apparently sustained by the absorption of the fatty tissues elaborated in summer. Indeed, as will be shown below, there is some reason to believe that the winter months are passed in partial or total torpidity.

9.-COLOR AND OTHER MINOR CHARACTERISTICS.

Color of Northern fish.

47. The adult menhaden is a most beautiful fish. Its color is pearly opalescent, like that of the cyprinoid fishes from which the commercial Essence d'Orient, or liquid pearl, used by artists, and in the manufacture of paste jewelry, is prepared. Each scale has all the beauty of a fine pearl, and the reflections from the mailed side of a fish just taken from the water are superb. The scales of the back and the top of the head are of a purplish blue. The blotch of black upon the scapular region, just above the origin of the pectoral, is very constant, although I have seen fish in which it did not occur. Many, especially the older and fatter ones, have a number of irregular, roundish, blue-black blotches upon the sides and flanks. The young fish are not so brilliantly colored, and, in general appearance, resemble the young of the shad.

Color of Southern fish.

48. Many of the Southern fish show metallic, brazen, and golden reflections from the flanks and fins. Agassiz's Clupanodon aureus, from Brazil, was similarly colored. The name "yellow-tail," commonly ap plied to this species in the Southern States, is in common use as far north as Cape Hatteras.

Axillary appendages.

49. In the axils of the paired fins are long differentiated scales, which cover the angles of the fins, and are evidently intended to promote swift