68 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



Zool. IST. Y. Fishes, iv, p. 344, pi. 58,- fig. 191 5 Stoker, Synopsis Fishes 

 N. A., p. 218; Thompson, Hist. Yt., part 1, p. 119. 



Acipenser ruthenus rnajor. — Forster, Phil. Trans., Ixiii, p. 149, 

 [Young.] 



Acipenser rupertiawLs. — Eichardson, Faim. Boreal. Auier. Add., p. 

 311, pi. 97, [Yoiiug:J Storbr, Syn. Fishes ISI. Am., p. 249, [Young.] 



Acipenser laevis. — Agassiz, Lake Superior, p. 267; Dumeril, Hist. 

 [tfat. Poiss., ii, p. 151, pi. 17. 



Acipenser car J) onarius. — Agassiz, Lake Superior, p. 271, pi. 5, [Young;] 

 Dumeril, Hist; Nat. Poiss., ii, p. Ill, [Young.] 



Acipenser rhynchwus. — Agassiz, Lake Superior, p. 276, [Yoiiug;] Du- 

 MERLL, Hist. Nat. Poiss,, ii, p. 179. 



Acipenser oxijrhijnchus. — Thompson, Hist. Vt., part i, p. 149. 



Acipenser viaculosus. — Gunther, [in part,] Cat. Fishes Brit. Mus. viii, 

 Po 339, [Young;] Dumeril, Hist. Nat. Poiss., ii, p. 114, [Young.] 



Acipenser anthracinus. — Dumeril, op. cit., p. 12G, pi. 15, [Young.] 



Acipenser megalaspis. — Dumeril, op. cit., p. 135, [Young.] 



Acipenser lamari. — Dumeril, op. cit., p. 139, [Young.] 



Acipenser Icirtlandii. — Dumeril, op. cit., p. 161. 



Acipenser nertianus. — Dumeril, op. cit., p. 162. 



Acipenser buffalo. — Dumi^ril, op. cit., p. 231, [Young.] 



(24 b.) Characters separating it from other American species. — In com- 

 parisons with the limited number of specimens of other species that are 

 available, the more prominent differences between this species and the 

 others were found to be in the following characters : 



In general form there is perhaps one American species, A. oxyrhynchus, 

 more elongate. The mouth is large, compared with the species mentioned 

 and with A. brevirostris. In the size of the area of naked skin around 

 the eyes and nostrils, it agrees with A. acutirostris, and differs from the 

 other American sturgeons, in which it is very perceptibly larger, appar- 

 ently reaching its maximum in A. transmontanus. 



A, oxyrhynchus, in the specimens at hand, is well distinguished from 

 the lake sturgeons, as well as other American species, in the proximity 

 of t-he frontal plates, usually merely separated by a naked strip of skin, 

 the last-mentioned character very marked in the young specimens. In 

 A. rubicundus and others, the ethmoid plate extends high up between 

 the frontals, separating them entirely. Exceptions to this fact are 

 very rare, the only one that has come under oiu" observation being 

 in a young specimen of A. maculosus, from the Ohio River. 



There are no i^lates surrounding the anus, as in A. oxyrhynchus and 

 A. brevirostris. In the fact of the presence of well developed shields 

 posterior to dorsal fin, it is different from A. transmontanns and A. medi- 

 rostris. The variations in the number of shields in the dorsal series, in 

 a very large number of observations at the lake-fisheries, was found to 

 be between 11 and 15, the number of 13 being found most frequently. 

 In this, though a variable character, it is pretty definitely separated 

 from the other species, except A. transmontanus and A. brachyrhynchns. 



