108 



MARINE AND FISEIERIE8 



6-7 EDWARD VII., A. 1907 



spots excepting the tail-fin and a portion of tKe dorsal fin. In many speciijiens the 

 dark lunar patches at the base of the tail still appear, while the dusky patch on thei 

 shoulder, absent in the herring, is distinct and remains in the adult. The very dis- 

 tinctive features referred to, and there are many others, are of aid in at once separat- 

 ing young gaspereaux from young herring of the same size with which they congregate 

 in estuaries and harbours, or from the young shad, which are natives of the same 

 rivers, though they do not seem to be as a rule found associated in the same schools 

 of clupeoid fry. 



The subsequent history of the adults of the clupeoids, whose life-history from the 

 ovum onward has here been sketched, furnishes one of the most important subjects for 

 marine biological research in the future. Apparently all alike resort to deep water, 

 only to return to the inshore areas as the spawning time approaches. Specimens may 

 be occasionally captured in estuaries and inshore areas long after the usual spawning 

 time; but their occasional character emphasizes the general rule. Like the salmon, 

 they disappear, and their whereabouts cannot be determined. With the return of the 

 spring or the fall spawning time the herring schools come in from their unknown 

 haunts, just as the shad and gaspereau revisit their chosen rivers in April and May, or 

 the pilchard and sprat congregate in their breeding areas in the open sea far out from 

 land, the former in May, June, July and later, and the latter in the earlier summer 

 months, though both these fish, like the smelt, come in from deep water for some un- 

 known purpose, when they are captured in immense quantities in October, November 

 and December; often indeed as early as the last week in September in the case of the 

 pilchard, or as late as the third week in J anuary in the case of the sprat. Reproduc- 

 tion and feeding are the two main purposes which stimulate the migrations of fishes; 

 but these do not explain the obscure movements referred to. Even Pennant ventured 

 to so surmise (Brit. Zoology, vol. III., 1759). Of the pilchard, he says, that * it appears in 

 vast shoals off the Cornish coasts about the middle of July, disappears the beginning 

 of winter, yet sometimes a few return again after Christmas. Their winter retreat is 

 the same as the herring, and their motives for migrating the same.' It is remarkable 

 that fishes so familiar as these clupeoids should present problems so difficult to solve; 

 but as Frank Buckland wrote, and the words are almost the last he ever penned : ' It 

 will be seen that we have a huge field of inquiry before us, the results of which will not 

 assume the form of a scientific plaything; but of a key by which we may hope to un- 

 lock the mysteries of the vast ocean.' 



(In the preparation of the plates I have utilized my own drawings made from the 

 specimens studied by me; but I have availed myself of the excellent figures published 

 in some of the memoirs referred to in the text. These last-named figures are as fol- 

 lows: Plate Vni,, figures 2, 3 after Mr. E. W. L. Holt, 4 after Dr. P. P. C. Hoeck; 

 6a, 6h after Dr. F. Raffaele, 8, 9 after Professor W. C. Mcintosh, 10 and 11 after Mr. 

 J. T. Cunningham; Plate IX., figures 12-16 after Dr. Ernest Ehrenbaum, 17-19, 21-22 

 after the late Prof. Eyder, 23-25 after Dr. P. P. C. Hoeck; Plate X., figures 36-38 after 

 Thaddeus Norris.— E. E. P.) 



LIST OF REFERENCE LETTERS. 



an. — ^anus. 



af. — anal fin. 



au. — otocyst or early ear. 



caps. — egg capsule or zona radiata. 



cf. — caudal fin. 



df. — dorsal fin. 



e. — eye. 



irnt. — intestine or digestive canal. 

 mn. — mandible or lower jaw. 



m^. — maxillary (upper jaw). 



not. — notochord. 

 og. — oil globule. 

 pf. — pectoral fin. 



pr. an. — ^pre-anal fin. 

 pvs. — ^perivitelline space. 



vf. — ventral fin. 

 yk. — ^yolk. 



