ON THE FOOD OF THE MENHADEN. 119 



bay side. At p is the same Peridinium, at h the infusorian Dinophysis, the same 

 abundance of m, a Godonella t, some of the diatoms at d, all gathered into this figure 

 from two fields of the microscope. 



Organisms from the stomach of a fish taken off Naushon Island, at the Weepecket 

 Islands, are indicated in fig. 11 — from a single field under the microscope. The Tin- 

 tinnodea (t) were remarkably abundant, the same diatoms as before were also very 

 numerous, as also the Ceratium fusus. That these of the three preceding figures are 

 the common unicellular organisms of the surface waters of this region of the bay in 

 which the fish were taken is shown in fig. 12, which represents some of the surface organ 

 isms filtered out of the water of the bay by means of the saud filter before described. 

 There are the same Peridinium p, Tintinnodea t and v, the same infusoria m and h, 

 the same diatoms Nitzschia, Synedra, Concinodiscus, Navicula, etc., d, together with 

 others not figured in the food material as found in the fish's stomachs, noticeably the 

 beautiful Chcetoceros. It is worthy of mention that the Tintinnodea figured were 

 relatively more abundant in the stomachs of the fish than in the filtrate from the 

 surface waters, and is perhaps to be explained by a different depth in which the fish 

 were feeding; or the fish having in every case fed at night, while the water filtered 

 was taken at daytime, these infusoria may have removed from the immediate surface 

 at the time the sample was taken. In the food here figured the crustacean elements 

 of it have been neglected, both because it is sometimes quite scanty and at other times 

 very abundant, even in the same locality, and is of the same general character in all 

 the localities studied, preeminently copepods, larval and adult. The minute Crustacea 

 are of course a favorite food of the menhaden, but no attempt has been made to illus- 

 trate it with the other organisms with which it is associated in the stomach of the fish. 

 That is to say, those portions of the field were selected for figuring in which the Crus- 

 tacea were absent. 



I shall, finally, illustrate this same point of the localization of littoral surface 

 organisms by .tfgures offering a similar comparison of some of the unicellular surface 

 organisms from a very long lagoon of brackish water at the eastern end of Marthas 

 Vineyard (at Vineyard Haven), in which menhaden in four different lengths, or stages 

 of growth, were taken, showing again the identity of those organisms in the alimentary 

 tract of the fish with those in the surrounding surface waters in which they were 

 feeding. There is considerable difference in the prevailing types, although, of course, 

 many of the species are common to it aud all the other localities studied. Some of 

 the organisms filtered from the surface waters are represented in fig. 13, selected from 

 various parts of a single slide of the microscope. The diatoms are beautifully rep- 

 resented by the chain d, composed of very large individuals unknown to me; these 

 are very abundant in this locality. Another chain, g, of a species unknown to me, is 

 also quite common, as is also the genus Laudcria (/). The Peridinium family is rep- 

 resented chiefly by the large, smooth, pinkish form divergens, with an occasional 

 Glenodinium, r, such as was found at the Acushnet River locality. At just below a is 

 represented the empty cell wall of a small vegetal organism, unknown to me, having 

 a peculiar rounded right-angled triangle shape, with .very thick walls. The Tintinnodea 

 are extremely abundant, too, in this locality, presenting a great variety of species; at 

 w is a Tintinnus; at v a peculiar kind, with a spiral marking and 2 whorls of an expan- 

 sion or flange on the test; those forms represented at t and c are also common. Taken 

 altogether, this lagoon exhibited one of the richest surface fauna* studied during 



