68 RErORT OF COMMISSIONER OF FISH AND FISHERIES. 



Zool. N. Y. Fislies, iv, p. .34i, pi. 58, fig. 191; Storek, Synopsis Fiislies 

 E". A., p. 218; Thompson, Hist. Vt., part 1, p. 119. 



Acipenser nifhen'is maj'.)r. — FORSTER, Phil. Trans., Ixiii, p. 119, 

 [Youiio:.] 



AcijH'user nipeyfiauus. — IIiciiardson, Faun. Boreal. Amor. xVdd., [>. 

 311, pi. 97, [Vouno-;] Storer, Syn. Fishes N. Am., p. 219, [Young.] 



Acipenser laeris. — AoAssiz, Lake Superior, p. 2G7; Dumeril, Hist. 

 Kat. Poiss., ii, p. 151, pi. 17. 



Acipenser carhonarius. — Agassiz, Lake Superior, p. 271, pi. 5, [Young; | 

 DuMERiL, Hist. Nat. Poiss., ii, p. Ill, [Yonng.J 



Acipenser rhijncha'us. — iVoASSiz, Lake Superior, p. 27C, [Young;] Du- 

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



Acipenser oxi/rJn/nchus. — Thompson, Hist. Vt., part i, p. 149. 



Acipenser maculosus. — Guntker, [in part,] Cat. Fishes Brit. Mas. viii, 

 p. 339, [Young;] Du3Ieril, Hist. Nat. Poiss., ii, p. Ill, [Young.] 



Acipenser anthracinns. — Ditmeril, op. cit., p. 12G, pi. 15, [Young.] 



Acipenser megalaspis. — Du:meril, op. cit., p. 135, [Y'oung.J 



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



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



Acipenser nertianns. — Dumeril, op. cit., p. 1G2. 



Acipenser hnff'aJo. — Dumeril, op. cit., p. 231, [Young.] 



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

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

 available, the more prominent differences between this species and the 

 others were found to be in tlie following characters: 



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

 more elongate. The mouth is large, com]>ared with Viw species mentioned 

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

 the eyes and nostrils, it agrees with A. acntirostris, and difters from the 

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

 ently reaching its maximum in A. transmontanus. 



A. oxi/rhynchusj in the specimens at hand, is well distinguished from 

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

 of the frontal plates, usually merely separated by a naked strip of skin, 

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

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

 the frontals, separating them entirely. Exceptions to this fact arei' 

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

 in a young specimen of A. 7nacnlosus, from the Ohio Elver. 



There are no plates surrouiuling the anus, as in A. oxyrhynchiis and 

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

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

 rostrls. 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, exce}>t A. transmontanus and A. brachyrhynchm. 



