250 CALIFORNIA ACADEMY OF SCIENCES. ' 



elliptical; outer lip thickened, smooth within; iiim r lip incrusted, smooth; columella only faintly 

 squamose, curved and slighdy twisted; canal rather short, narrow. 



Dimensions. — Long. 33 mm.; lat. 15 mm.; body-whorl 23 mm.; aperture, including canal, 

 18 mm.; canal 7 mm.; defl. 44 degrees. 



The largest of the Troplwns so far found in this locality. The adult of this 

 shell resembles var. prrecur^ior, but is distinguishable from that species by its larger 

 size, heavier shell, more prominent spiral ridges, pro23ortionally shorter canal, and in 

 having the angle near the middle of the wiiorl, rather than posterior to the middle; 

 distinguishable from 2\ ^tiuirti by heavier shell, more numerous and much heavier, 

 lower and more rounded, transverse ridges, shorter canal, and by having the angle in 

 the middle of the whorl. The young of T. cerritensis resembles 7\ i^edroana some- 

 what, but may be distinguished from that species by its heavier shell, more depressed 

 outline and much shorter canal. An adult found at Los Cerritos has fewer transverse 

 ridges and a higher angle than the type. Type from lower San Pedro series of 

 Deadman Island. Said by Dr. Dall to be near 2\ craticnlattis Fabricius. 



One adult specimen (type) and five juniors found in lower San Pedro series 

 at Deadman Island; one specimen from Los Cerritos in ujiper San Pedro series. 

 The specimen figured is the type, whicii In from the lower San Pedro series at 

 Deadman Island, and is now in the United States National Museum. 



Pleistocene. — San Pedro (Arnold). 



250. Trophon (Boreotrophon) gracilis Perry. 



Plate VI. Fig. 8. 



Polyplex gracilis Perry, Conch , PI. IX, fig. 4. 



Trophon 7n7tllicostatus (noi oiK^CH.) Gxhh. Pal. Cal., Vol. II, p. 70, 1S69 (in part). Cooper, 7th 

 Ann. Rept. Cal. St. Min., 1888, p. 26S (in part). 



Shell of medium size, lusilorm; sp're elevated; whorls five or si.x, sharply angular, crossed 

 by eight or nine frill-like varices, which fle.x forward and are only slightly ccjronate on angle; surface 

 smooth; suture deeply impressed, giving tabulate appearance to upper part of whorl; apertura 

 elliptical; outer lip effuse, smooth within; inner lip smooth; columella long, slightly twisted; canal 

 long, narrow, recurved. 



Dimensions. — Long. 26 mm.; lat. 13 mm.; body-whorl ig 5 mm ; aperture 16.2 mm.; canal 

 7.7 mm.; defl. 62 degrees. 



Distinguishable by frill-like varices and lack of spiral sculpture. Specimens 

 identified by Dr. Dall. This species is the T. mii Uicostatus of most western col- 

 lectors. It differs from that species in having fewer, but more prominent varices, 

 and in being a broader shell. 



Rare in Pliocene and lower San Pedro series of Deadman Island. Found 

 also in the Pleistocene at bath-house, Santa Barbara. The specimen figured is from 

 the Pliocene of Deadman Island, and is now in the collection of Delos Arnold. 



Livvir/. — Circumpolar; Sitka to Monterey (Cooper). 



Pleistocene. — Santa Barbara (Cooper; Arnold): San Pedro (Arnold). 



Pliocene. — San Pedro (Arnold). 



