MAZATLAN UNIVALVES 273 



by Messrs. Adams. No specific difference can be traced be- 

 tween the Sandwich Island specimens, those from Mauritius, 

 and the abundant forms from S. America. The species does 

 not affect the Northern hemisphere. It is not quoted by 

 C. B. Adams in his Panama list. The solitary specimens from 

 Guinea, Mazatlan and California may have been imported. Of 

 the two Larnarckian names, the first is chosen, although very 

 imperfectly described from a single specimen in the collection 

 of Mde. de Bandeville, because it well expresses the usual 

 character of the species, and has been adopted by D'Orbigny. 

 Long. 1*42, lot. 1'2, alt. '68. 



Hob. S. America, D'Orbigny. Mazatlan ; 2 large but dead 

 specimens ; L'pool Col. Lower California; 1 dead specimen ; 

 Major Rich. (C. Peruviana.) Peru, Dombey. Peru and 

 Chiloe, Bern. Philippi. (1 sp.) Loander, Tarns. (C. patula) 

 Otaheiti, Lesson. (C. strigata.) Valparaiso ; on Mytili, 

 3 6fm. ; Cuminq. (C. pallida.) Falkland Is. ; under stones ; 

 Cuming. (C. arcuata.) Payta, Peru, D'Orbigny. (C. lineo- 

 lata.) South Seas, Deshayes. 



Tablet 1353 contains a specimen, with attachments of two 

 others on its back. 



336. CBEPIDTJLA PDOESATA, Brod., var. BILOBATA. 



C. t. tenui, subcirculari, subdiaphand, albidd, scepe fusco 

 radiatd sen maculata, ; vertice nucleoso globoso, satis magno, 

 apice subdepresso, anfractibus rapide augentibus, vix extante, 

 haud prominente, a margine valde remoto ; Icevi, sen striis incre- 

 menti, interdum lamellis irregularibus ; hue et illuc vix radiatim 

 striatd, seupropter sedem quasi costatd ; lamind tenui, bilobatd, 

 lobd posteriori parvd, anteriori maxima, ad extremitates sinu- 

 atd, apicem versus impressd, incrementi lineas manstrante. 

 Calyptrsea dorsata, Srod. Proc. Zool. Soc. 1834, p. 38 : Trans. 



Zool. Soc. vol. i. p. 202, no. 20, pi. 28, f. 10. 



About a dozen young specimens of this species were found 

 in the shell washings ; but some beautiful ? adult shells are in 

 Mr. Cuming's Col. The form is intermediate between Crepidula 

 and Crucibulum, the young state of which it greatly resembles. 

 The lamina is attached by less than one half of its total 

 length ; and the vertex is situated about half way up the 

 height of the shell. The above diagnosis was written in ignor- 

 ance of Broderip's species, which (with others) had been lost 



