250 CALIFORNIA ACADEMY OF SCIENCES. 



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

 squamose, curved and slightly 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 lai'gest of the Trophons so far found in this locality. The adult of this 

 shell resembles var. praicia^sor, but is distinguishable from that species by its larger 

 size, hetivier shell, more prominent spiral ridges, proportionally shorter canal, and in 

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

 distinguishable from 7'. Mnarti 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 1\ pedroana some- 

 what, btit 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. Stiid by Dr. Dall to be near T. craticulatus Fabricius. 



One adult .sj^ecimen (type) and five juniors found in lower San Pedro series 

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

 The specimen figured is the ty2ie, which is from the lower San Pedro series at 

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



Pleistocene. — San Pedro (Arnold). 



250. Trophon (Boreotrophon) gracilis Pcmj. 



Plate YI. Fig. S. 



Polyp/ex gracilis Perry, Conch., PI. IX, fig. 4. 



Trop/ion niu//icosia/iis {noi ofEscH.) Gabh. Pal. Cal., Vol. II, p. 70, 1S69 (in part). Cooper, 7th 

 Ann. Rept. Cal. St. Min., 18S8, p. 268 (in part). 



Shell of medium size, lu^iform; spire elevated; whorls five or si.\, sharply angular, crossed 

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

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

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

 long, narrow, recurved. 



Dimensions. — Long. 26 mm.; lat. 13 mm.; body-whorl 19 5 mm ; aperture 16.2 mm.; canal 

 7.7 mm.; defl. 62 degrees. 



Distinguishable by frill-like varices and lack of spiral sculj^ture. Specimens 

 identified by Dr. Dall. This species is the T. mu/ticostatus of most western col- 

 lectors. It differs from thtit 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 Btirbara. The specimen figured is from 

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



Liinng. — Circurapolar; Sitka to Monterey (Cooper). 



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



Pliocene. — San Pedro (Arnold). 



