1064 BULLETIN OF THE BUREAU OF FISHERIES. 



museum it could not be a distinct species, and another that the American authors 

 were incompetent to determine the species. 



It might be thought that related species would agree at least in the char- 

 acter of their eggs and oviposition, but exceptions to this also occur. A notable 

 case is manifest among the clupeids. There are several species of the northern 

 seas so closely related that they are associated by most ichthyologists except in 

 America in the same genus — Clupea. Nevertheless there are remarkable differ- 

 ences between species in their eggs, as well as in the manner of depositing them. 

 The typical herrings {Clupea harengus and Clupea pallasi) have opaque eggs 

 destitute of oil globules, deposited in the sea in water of moderate depth and 

 adhering in masses to foreign bodies at the bottom; the pilchards (Clupanodon 

 pilchardus, etc.) have translucent eggs, buoyant by oil globules, and cast near 

 the surface of the sea often quite far from land and there hatched; the shads 

 (Alosa species) leave the sea and ascend rivers to deposit their eggs near or on 

 the bottom in fresh water; the alewives and hickory shads (Pomolobus) are also 

 anadromous and agree in most respects with the shads. 



Another requisite, too often overlooked for the successful historian of a 

 fish's habits, is that the species in question should be correctly identified or the 

 means for identification furnished. Many instances might be given of inter- 

 esting details of habits of animals worthless to science because the species are 

 not recognizable. Only one such need be mentioned and that because it has 

 recently come up for notice. Many years ago (in 1874) a French amateur 

 naturalist, Carbonnier, published some remarkable details of the breeding habits 

 of fish received from New York which he called "la Fondule (Fundula cyprino- 

 donta, Cuv.)." I have been frequently appealed to for information as to the 

 proper name of that fish. No such fish was described by Cuvier and apparently 

 the Frenchman had been informed by some one, in an offhand manner, that it 

 was a Fundulus — a cyprinodont — and had been satisfied with the suggestion 

 and even misinterpreted the statement. In fact, the fish was not a cyprinodont 

 at all, although having a considerable superficial resemblance to one, but an 

 umbrid, the common Umbra pygmaa of New York. To this day, so far as 

 published records show, Carbonnier is the only man who has succeeded in 

 breeding this fish, but his record was long unusable because it was not known 

 what fish he really had. 



Another fault we must take care to guard against is the counterbalance- 

 ment of a difliculty against a certainty. Many examples of this are to be met 

 with in the history of the common eel. Several are still persistent. 



The breeding resorts of the eel of northern Europe have been discovered 

 within the last two years, thanks to the International Council for the exploration 

 of the North Sea and the excellent work of Johannes Schmidt ; they are in the 

 ocean at "depths of at least about 1,000 meters (corresponding to a pressure 



