86 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 



Fuiera rougbish, not enlarged. Lower lobe of tail rather sliarj). Sides 

 of tail with regular rhombic plates. Plates mesocentrous, rather rough. 

 Anal smaller than dorsal, placed mostly below it. Anterior rays of 

 pectoral thickened. "Skin with very small rough points in very 

 young examples ; in older ones these ossifications are broader, rough, 

 substellate, and more or less regularly arranged in oblique series." D. 

 40-44; A. 2G-30. Dorsal plates 11-14; lateral 27-36; ventral plates 

 11. Atlantic Ocean ; ascending rivers of Europe and North America. 

 Var. ©xyrj'SiyfiacBiMS (Mitchill), the American Sturgeon, has the num- 

 ber of lateral plates generally fewer — 27-29 instead of 29-36, as in Euro- 

 pean examples. The stellate ossifications are also said to be some- 

 what rougher than in the European form. Massachusetts to Florida ; 

 abundant. 



(L. Syst. Nat. ; Giinther, viii, 342 : Aoipenser oxyrhynchus Mitchill, Trans. Lit. & 

 Phil. Soc. N. Y. i, 462, and of most American writers.) 



75. A. traaisanoaita.llUS Richardson. — White Sturgeon; Columbia River Sturgeon; 

 Sacramento Sturgeon. 



Color dark grayish, scarcely olive-tinged, and without stripes. Dor- 

 sal shields mesocentrous, with a compressed bluntish spine, which is 

 anteriorly often serrated, and followed behind by a compressed keel. 

 Lateral shields rather opisthocentrous. Skin with stellate roughnesses, 

 but smoother than in A. medirostris. Snout sharj) in the young, be- 

 coming rather blunt and short in the adult, when it is considerably 

 shorter than the rest of the head. Barbels rather nearer to the tip of 

 snout than to the mouth. Gill-rakers comparatively long, more than 

 3 times as high as broad, about 26 in number. Upper lobe of tai[ 

 with rhombic plates. First caudal fulcrum, above and below, enlarged 

 and granular. Lower lobe of caudal rather sharj) and long, not much 

 shorter than ui:)per. Dorsal plates 12 ; lateral 36-49, usually about 44 ; 

 ventral 10. Anal fin mostly below dorsal. D. 45 ; A. 28. Depth 7 in 

 length ; head 4. Pacific coast, south to Monterey, ascending the Sacra- 

 mento, Columbia, and Eraser's Eivers in large numbers in spring. 

 Beaches a weight of 300 to 600 pounds, and is used as,food. 



(Richardson, Fauna Bor.-Amer. iii, 278, 1836: Acipenser hrachyrhynchus and acvH- 

 ros^m (young) Ayres, Proc. Cal. Acad. Nat. Sci. 1854,15,16: Acipenser transmontanus 

 and hrachyrliynchus Giinther, viii, 336, 337.) 



"76. A. mc^rostris Ayres. — Green Sturgeon. 



Color olive-green, with an olive stripe on the median line of the belly 

 and one on each side above the ventral plates, these stripes ceasing op- 

 posite the vent. Shields generally opisthocentrous, with a strongly 



