STURIONIDE^E. 281 



It disappears about the month of September. It is termed by the Cheenooks 

 katlook, and in the language of the Cascade Indians naJchun." — The Columbia 

 River sturgeon belongs either to the sturiones or sterletce, two of the four groups 

 into which Brandt has divided the genus, the approximation or remoteness of the 

 shields by which these two forms are characterised not being very precise as a prac- 

 tical mark of distinction *. Its snout is broad as in the Common sturgeon A. sturio, 

 but much more depressed, and its mouth is comparatively large. In its general 

 form and proportion of parts it strongly resembles A. Ruthenus, but whether it be 

 the same with the sturgeon of Stewart's Lake and Frazer's River, noticed in page 

 "215, we have no means of ascertaining. 



DESCRIPTION 

 Of No. I, specimen of A. transmonlunus from the Columbia River. 



Form elongated, tapering from head to tail, the body keeled by five rows of shields, the 

 dorsal row being the most prominent, and the lateral one least so ; the belly and under sur- 

 face of the head are flattish; the cheeks are also fiat, and the snout rounds off laterally from 

 the nostrils, terminating in a moderately-acute point ; the top of the head is slightly convex, 

 both longitudinally and transversely, with a shallow depression extending from between the 

 orbits backwards on the mesial line ; the profile shelves off suddenly before the nostrils into 

 the greatly-depressed snout, which, when seen from above, is semilanceolate, its breadth at the 

 nostrils being equal to its length anterior to these openings; in profile the snout appears thin 

 and horizontal, but its flexible point is readily turned up a little. Two pairs of slender, taper- 

 ing barbels, quite simple at their tips f, hang from beneath the snout about midway between 

 its point and the orbit ; the exterior pair, which are a little posterior to the others and rather 

 longer, measure an inch and a half. A bone, forming a narrow, even, flat ridge, is per- 

 ceptible through the skin covering the under surface of the snout, and terminates abruptly 

 opposite to the anterior margin of the orbit, on the verge of the large cavity in which the 

 mouth is lodged. The snout, if measured from the orbits, forms one-twelfth of the total length 

 of the fish, but less than one-fifteenth if measured only from the nostrils. The mouth is pos- 

 terior to the eye, and when protruded has an oval orifice, whose axis lying transversely mea- 



* Professor Lovetsky, adopting Brandt's subdivision, has given the following arrangement of the species known to 

 him: — 



1. Husones. — Snout acute or obtuse, wholly or partly cartilaginous, more or less pellucid; shields which arm the 

 body distant from one another. A. huso, Linn.; A. husoniformis, Lovet. ; A. dauricus, Georg.; A. obtusiroslris, Le 

 Sueur; A. rubicundus, Le Sueur. 



2. Sturiones. — Snout obtuse or awl-shaped, covered with bony shields not pellucid ; shields distant. A. Gulden- 

 stddtii, Brandt ; A. sturio {A. Lichlensteimi, Schn., Bi.) ; A. sclupa, Gui.denst. ; A. Gechelii, Fn.x. 



3. Steri-et^e. — Snout awUshaped, covered with bony shields, not pellucid; shields imbricated. A. Ruthenus, Linn. ; 

 A. acutealus, Fischer. 



4. Helopes. — Snout long (one-sixth or one-seventh of the length of the body), covered with strong bony shields ; 

 shields distant. A.stellatus, Pali..; A. oxyrhynchus, Mitch.; A. maeulosus, Le Sueur. (Lovetsky, Xouv.Mtm.de 

 Moicou, iii., p. 257. An. 1834.) 



f The barbels of A. Ruthenus have fringed tips. 



2o 



