ACM.KA. 25 



Internally smooth or furnished with grooves radiating from the 

 apex more or less strongly marked. Muscular impressions deep, 

 strong, horse-shoe-shaped, with the marks of the anterior ends of the 

 adductors rounded and broader than the rest, connected by a slender 

 impressed line marking the attachment of the mantle. Young shells 

 are .often furnished with irregular riblets more or less strong, many or 

 few in number, radiating from the apex, but stronger towards the 

 margin. Color dead-white inside and out, often livid or tinged a 

 fine pink or pea green from Nullipore, never wax-yellow or horny- 

 pellucid as in the normal state of Scurria scurra. 



Length 35, breadth 31, alt, 23 mill. 



Length 23, breadth 20, alt. 17 mill. 



Aleutian Is. to San Diego, California. 



A. mitra ESCH. in Rathke, Zool. Atl. pt. v, p. 1 18, t. 23, f. 4. 

 DALL, Amer. Jour. Conch, vi, p. 241. A. mammillata ESCH., I.e. p. 

 18. A. marmorea ESCH., I. c. p. 19 Scurria mitra GRAY, ADAMS, 

 CARPENTER etal. S. f mitra DALL, Amer. Jour. Conch, v, p. 149 

 (dentition) Lottia conica GLD., (part) Moll. U. S. Expl. Exped. p. 

 346. S. mitra var. tenuisculpta CPR. Amer. Journ. Conch ii, p. 346. 

 Scurria f fwiiculata CPR. Proc. Cal. Acad. Sci. iii, p. 214, 1865 ; 

 Brit. Asso. Rep. 1863, p. 650 ; Amer. Jour. Conch, ii, p. 347. 



The shell of this conical white species is very distinct from the 

 others inhabiting West America. It resembles Scunda scurra Less., 

 of Chili in form, but has not the waxen-yellowish outer layer of that 

 species. The largest specimen I have seen measures, length 45, 

 breadth 41, alt. 28 mill. 



Var. TENUISCULPTA Cpr. Sculptured with distant radiating striae 

 or lirulse. 



Var. FUNICULATA Cpr. Shell small, whitish, regularly conical, 

 apex acute, elevated, a little in front of the middle; sculptured with 

 strong rounded riblets, sometimes a little nodulous ; sometimes single, 

 sometimes gathered into two's and three's ; with wide interspaces in 

 which intercalary riblets appear. Length 6, breadth 4$, alt. 3 mill. 



Monterey, California. 



A curious small shell, having the contour of A. mitra, but with 

 strong, smooth, crowded unequal ribs. The measurements are from 

 the type in the Smithsonian Institution. 



