1889.] NATURAL SCIENCES OF PHILADELPHIA. 249 



a little more than half length of dorsal, and placed almost entirely 

 under it. Color, sides, back, olive-brown, belly, whitish, sturio, 3. 



bb. Space between dorsal and lateral shields with minute spicules 

 in very many series. 



d. Last dorsal shield of moderate size, more than half length of 

 one before it. Dorsal shields 15 (11-16) ; lateral shields 38 (30-39) ; 

 ventral shields 10 (9-11). D. 35; A. 27. Shields large, rough, 

 with strongly hooked spines, becoming later comparatively smooth: 

 Ventral shields growing smaller with age, and finally deciduous. 

 Snout slender and long in the young, becoming quite blunt with age, 

 when it is considerably shorter than the head. Anal 1 2 in dorsal 

 and beginning about its middle. Color blackish above, sides paler or 

 reddish with irregularly distributed black spots. rubicundus, 4. 



'/'/. Last dorsal shield very small, less than half length of one 

 before it. Dorsal shields 11 (8-11) ; lateral shields 32 (22-33) ; 

 ventral shields 9 (6-9) ; D. 41 ; A. 22. Shields large and flat ; their 

 spines not well developed. Snout short and blunt, about one-fourth 

 length of head. Anal 2 in dorsal and placed entirely under it. Color 

 blackish above, whitish below. brevirostrum, 5. 



aa. Plates between ventrals and anal small, in two rows of 4 to 

 8 in a row ; space between dorsal and lateral shields with stellate 

 plates of moderate size in about 5 series interspersed with many 

 smaller ones ; last dorsal shield less than half length of one before 

 it. Dorsal shields 11-12 ; lateral shields 40-50 ; ventral shields 10- 

 12. D. 44-49 ; A. 28-30. Dorsal shields large and flat : shield- 

 spines but moderately developed ; snout sharp in the young, becom- 

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

 shorter than the rest of the head. Base of anal fin 2 in dorsal and 

 placed wholly under it. Color dark grayish, scarcely olive-tinged, 

 and without stripes. transmontanus, 6. 



2. Acipenser medirostris. Green Sturgeon. 



An/a nsrr medirostris Ayres, Proc. Cal. Acad. Xat. Sci. 15, 1854 

 (San Francisco); Girard, Pacif. R. R. Survey, 356, 1859 (San 

 Francisco) ; Duineril, "Xouv. Arch. Mas. III. 167, pi. 13, f. 2, 1867 ; " 

 Dumeril, Hist. Poiss. II. 222, 1870 (San Francisco) ; Giinther, Cat. 

 Fish. Brit. Mus. VIII. 342, 1870 (California) ; Jordan and Jouv, 

 Proc. U. S. Xat. Mus. li\, 1881 (San Francisco); Jordan and 

 Gilbert, Proc. U. S. Xat. Mus. 36, 1881 (Sacramento, Columbia and 

 Frazer's rivers) ; Bean. Proc. U. S. Xat. Mus. 160, 1881 (copied); 

 Jordan and Gilbert, Svnop. Fish. X. Amer. 86, 1882; Jordan, Cat. 

 Fish. X. Amer. 13, 1885. 



