264 MAZATLAtt UNIVALVES 



adopted from their great convenience. Of Calyptraea proper, 

 which is the best marked in its characters and is well repre- 

 sented both in individuals and species in the Caribbean and 

 equatorial West American Seas, only a single individual was 

 found in the entire Mazatlan collection. None of the species 

 were found with a solid shelly attachment, though a thin 

 deposit may sometimes perhaps be traced. In general a cavity 

 is excavated on the backs of other sheDs. 



FAMILY 

 GENUS TEOCHITA, Schum. 



Schum. Ess. no. 11, 1815. Gray, Proc. Zool Soc. 1847, p. 158, 



no. 272. Phil. Eandb. Conch, p. 187. JZ". fy A. Ad. Gen. i. 



367. 

 Trochus, pars, Lam. Calyptrsea, pars, Desk. Sigapatella, Lest* 



1829, Voy. Coq Trochatella, Less. 1830, (teste Gray.) In- 



fundibulum, D'Orb. 1846, non Montf. 



This genus forms an exact transition in the shell from the 

 spiral Crepidulse to the Phoridse, the animal of; which is 

 widely different. It is in fact a Crepidula, with the anterior 

 part shortened, while the posterior is lengthened. Several 

 species might be ranked with either genus. It is represented 

 in the Mazatlan collection by a single specimen. 



331. TEOCHITA VENTEICOSA, n. s. 



T. t. ventricosd, subdepressd, irregulari ; albidd, castanco 

 tmbutd ; anfractibus iii. [? aut pluribus} ventricosis, maxim* 

 prope suturam ad any. 90 depressam ; superficie irregulariter 

 noduloso-rugosa, rugis subobsolelis, diagonalibus, nodulis hue et 

 illuc prope suturam extantibus ; totd pagind creberrime et 

 minutissime corrugatd; epidermide lamellosa, cornea, maxime 

 prope marginem, indutd ; cavitate concavo ; lamina albd, tineas 

 incrementi haud monstranti> labioparum reflexo^umbiliconullo; 

 mar gine forma sedis convenicnte. 

 Conrp. Trochita radians, (Desk, teste H. SfA.Ad. Gen. i. 367,) 



DJcr. Ind. Moll. Guin. p. 36, no. 97: = Trochus r. Lam. An. 



s. Vert. (ed. I,) vol. vii. p. 11, no. 5 : Sckub. fy Wagn. 



Chemn. Suppl. pi. 229, f. 4063 : = Calyptrsea r. Lam. ed. 



Desk. vol. vii. p. 626, no. 8 : =Infundibulum r. Zool. Beech. 



Voy. p. 148, pL 39, f. 10, 11 : =PateUa trochiformis, Chemn. 



