276 MAZATLAN UNIVALVES 



the colour lighter than in C. incurva, and disposed to break up 

 into spots ; shaped like Emarginula rosea, with a very recurv- 

 ed, distant and projecting vertex, a short, deeply sunk and 

 slanting deck, and a hole abov^ it passing up the spire. The 

 characters are like some of the forms of Cr. incurva intensified ; 

 and are subj ect to considerable variation. The mode of growth 

 is as in that species ; but the planorbiform vertical whirls 

 are even smaller, (about '01 across) with the apex deeply 

 sunken. The smallest specimen is *15 in length ; the largest 

 found measures long. '84, lot. '62, alt. '46. 



Aflatsp. '62, '48, "18, 



The shortest-decked specimen measures '16 from deck margin 

 to the posterior, '39 to the anterior end, with an apical projec- 

 tion of *14. 



Hob. Bodegas, California ; attached to dead and living shells 

 and to each other, 6-10 fm. ; Hinds. Straits of De Fuea, 

 G-ould.Sta, Barbara, Col. Jewett Panama, extremely rare, 

 C. B. Ad. Mazatlan ; extremely rare ; Upool Col. 



Tablet 1357 contains 2 sp. very young. 1358, 1 sp. flat, 

 margin extended. 1359, 1 sp. compressed, dark brown. 1360, 

 the largest sp., twisted growth, slightly ribbed and corruga- 

 ted. 1361, 1 sp. pale flesh colour. 



339. CEEPIDULA INCUBVA, Brod. 



Calyptrsea (Crepidula) incurva, Brod. Proc. Zool. Soc. 1834, 



p. 40 -.Trans. Zool. Soc. vol. i. pi. 29, f. QMilll. Syn. Nov. 



Test. Vw. p. 150. 

 Crepidula incurva, B. M. Cat. TfOrl. Moll. p. 49, no. 421. 



C. B. Ad. Pan. Shells, p. 228, no. 347 (Crypta i.) H. $ A. 



Ad. Gen. i. 369. 

 =- Crepidula hepatica, MenJce, (non Desli. nee C. B. Ad. nee 



Krauss,) Zeit.f. Mai. 1847, p. 184, no. 33. 



This species is known normally by the sharp longitucMaal 

 ridges on the back, which are not dependent on the attachment, 

 being regular in growth, and conspicuous when adherent OIL 

 smooth shells. It is much smaller than C. onyx, of a deeper 

 chocolate brown colour, convex, with the beak very prominent, 

 smooth and black as in C. rugosa, Nutt. The epidermis is 

 rather thin and deciduous. There are however so many speci- 

 mens in which one or other of these characters pass away, that 



