226 CALIFORNIA ACADEMY OF SCIENCES. 



209. Fusus robustus Trask. 



Fustis robuslHS Trask, Proc. Cal. Acad. Sci., Vol. I, 1855, p. 41. Cooper, 7th Ann. Rept. Cal. St. 



Min., 1888, p. 241. 

 Fusus kobelli {nor. of Dall), of Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 240 (in part). 



.Shell of medium size, elongate-fusiform, thick; whorls about six, convex, crossed by eight 

 or nine prominent rounded ridges which are most prominent on angle of whorl (these ridges are 

 sometimes obsolete on the anterior part of the body-whorl); spiral sculpture consists of four to six 

 prominent raised lines, with sometimes smaller lines intercalated; suture appressed, deep, distinct; 

 aperture pyriform; outer lip smooth on inner edge, but with numerous spiral ridges further in; inner 

 lip smooth; columella spirally ridged externally; canal rather short, narrow. 



Dimensions. — Long. 34 mm.; lat. 14 mm.; body-whorl 22.5 mm.; aperture, including canal, 

 17 mm.; canal 5 mm.; defl. 40 degrees. 



Distinguishable from F. rugosus by smaller size, heavier shell, lack of promi- 

 nent angular appearance of whorls and ridges near posterior suture, less number of 

 whorls and relatively shorter canal. Upon examining a large series of this species 

 and of F. i-agosus the writer has no hesitancy in separating these two forms of Trask's. 

 Distinguishable from F. kobelii by deeper appressed suture, stronger, revolving ridges, 

 narrower form, and lack of wavy sutural band on posterior edge of wliorl. F. robustus 

 is probably a j^recursor of F. kobelti. This species has been identified as F. ambustus 

 by many West Coast couchologists, including Cooiier and perhaj^s Carpenter. Speci- 

 mens identified by Dr. Dall. 



Found only in the upper San Pedro series; rather common at Old San Pedro. 

 Found also in the Pleistocene at the bath-house, Santa Barbara. 



Living. — Santa Barbara to San Diego (California State Museum). 



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



210. Fusus rugosus Trask. 



Plate IV, Fii:. 7. 



Fusus rug-osus Trask, Proc. Cal. Acad. Sci., Vol. I, 1855, p 41. Cooper, 7th Ann. Rept. Cal. St. 

 Min., 1888, p. 241. 



Shell of medium size, elongate, fusiform, thin; whorls eight, convex, crossed by eight to 

 eleven rounded ridges, which rise to greatest prominence on upper side of whorl; body-whorl ventri- 

 cose and sometimes lacking transverse ridges on forward part; surface ornamented with several 

 prominent raised lines, with fine lines sometimes intercalated; suture deeply appressed, wavy; 

 aperture elliptical; outer lip thin, with interior spiral ridges extending nearly to rim; inner lip smooth; 

 columella long, slightly twisted, spirally ridged; canal long, narrow, slightly curved. 



Dime7isions. — Long. 50 mm.; lat. 19 mm.; body-whorl 35 mm.; aperture, including canal, 

 28 mm.; canal 13 mm.; defl. 44 degrees. 



The specimen described and figured is a small one. Some of the specimens 

 are over 65 ram. in length. 



Distinguishable from F. robustus by larger size, thinner shell, longer canal, 

 more ventricose body-whorl, and greater development of transverse ridges on u[)per 

 portion of whorl. Perhaps F. rugosus is the precursor of F. robustus. If so, then 



