44 Panama Shells. MITRID.E. 



between these species. We will venture to add that while 

 the species are clearly distinct, they constitute one of those 

 interesting pairs of analogues, which inhabit opposite sides of 

 the Isthmus of tropical America. 



M. granulosa we believe to be exclusively a Caribbean 

 species, although Kiener says " Habite les mers de 1'Inde et 

 de la Nouvelle Zelande, de la Guadeloupe, de la Trinite et du 

 Mexique." 



19. Mitra solitaria. Nov. sp. 



Shell rather slender, fusiform : of a very deep blackish 

 brown, less deep in the aperture, and quite pale on the plaits : 

 with very numerous small transverse ribs, which are obsolete 

 anteriorly, and which are granulated by revolving striae, that 

 are obsolete in the interspaces posteriorly, and are strongly de- 

 veloped anteriorly, with microscopic incremental striae ; apex 

 acute : whorls ten, moderately convex, slightly shouldered 

 above, with a moderately impressed suture : aperture long, 

 with a rather short canal : labrum thick, with numerous sharp 

 plaits inside, with a sinus near the posterior end : columella 

 with four plaits. Length .68 inch ; breadth, .23 inch ; length 

 of aperture, .34 inch. 



Station. Under stones near low water mark we found this 

 elegant and rare shell. 



Habitat. Panama ; C. B. A. ! 



We found a single specimen on the reef. 



20. Ulitra trisiis. 



Synonymy. 



Mitra tristis Brod. in Proc. Zool. Soc. Lond. p. 194. Dec. 1835. 



Reeve Conch. Icon. pi. 15. f. 114. Sept. 1844. 



Station. In sandy mud at the depth of 6 to 10 fathoms; 

 Cuming ! Broderip ; also Reeve. We found sev- 



