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 8. America. The species does. 
not affect the Northern hemisphere. It is not quoted by 
C. B. Adams in his Panama list. 'Che solitary specimens from 
Guinea, Mazatlan and California may have been imported. Of 
the two Lamarckian 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 DiOabigny. 
Long. 1°42, lat. 1°2, alt. °68. 
Hab.—S. America, D Orbigny.—Mazatlan ; 2 large ae dead. 
specimens ; L’pool Col.— Lower California: if dead specimen ; 
Major Rich. —(C. Peruviana.) Peru, Dombey. — Peru and 
Chiloe, Bern. Philippi.—(1 sp.) (C. patula) 
Otaheiti, Lesson.—(C. strigata.) Valparaiso ; on Mytili, 
3—6fm.; Cuming.—(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. CREPIDULA ?DORSATA, Broel., var. BILOBATA. 
C. t. tenwt, subcirculari, subdiaphand, alhidd, sepe fusco 
radiatd seu maculatd; vertice nucleoso globoso, satis magno, 
apice subdepresso, anfractibus rapide augentibus, vix extante, 
haud prominente, a margine valde remoto ; levi, seu striis incre- 
menti, interdum lamellis trreqularibus ; hae et iltue vie radiatim 
striaté, seu propter sedem quasi costaté s lamind tenui, bilobaté, 
lob& posteriori parva, anteriort maxima, ad extremitates sinu- 
atd, apicem versus impressd, incrementi lineas monstrante. 
Calyptrea dorsata, Brod. Proc. Zool. Soc. 1834, p. 38 :— Trans. 
Zool. Soc. vol. i. p. 202, no. 20, pl. 28, f. 10. 
About a dozen young specimens of this species were found 
in the shell washings ; but some beautiful Padult 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 
