184 MAZATLAN UN T VALVES 



Ordinary state. Tablet 851 contains 3 sp. light brown. 

 852, 4 do. darker. 853, 4 do. whitish margin. 854, 4 do. broad 

 white margin. 855, 4 sp. blackish brown, white margin. 856, 

 4 do. penciled. 857, 4 do. tessellated. 858, 4 do. nearly black. 



Specimens shewing exterior. 859, 3 sp. fine growth, with 

 epidermis. 860, 4 do. principal ribs few. 86J, 5 do. more 

 numerous. 862, 5 do. principal ribs scarcely developed. 863, 

 1 do. with very fine crowded riblets, here and there developing 

 into principal ribs. 864, 2 sp. very conical. 



Tablet 865 contains 4 sp. probably belonging to this species, 

 but approaching S. aequilirata. Principal ribs scarcely traceable. 



240. SlPHONAKIA ^QUILIKATA, n. S. 



S. t. subconicd, ovali, regulari, liris numerosis subrugulosis, 

 fequalibus, radiatim ornatd, interstitiis haud latis, Icevibus ; 

 fusco-olivaced, liris altis ; epidermide tenui, adh&rente ; pagind 

 internd fused, vix iridescente ; margine crenulato ; canali sub- 

 centrali, extus haud prominent l e. 



One specimen of beautiful growth in the Mazatlan collection 

 agrees with a larger but somewhat irregular one in that of 

 Mr. Cuming, in characters which appear to separate it from 

 all varieties of S. Lecanium. Eiblets equal, interstices smooth, 

 channel nearer the middle and not conspicuous either by 

 swelling or special marking outside. The Mazatlan specimen 

 has much broader interstices than that of Mr. Cuming ; but as 

 the riblets are bifurcating, it is probably not fully grown. 

 There is no trace of striulse. The examination of more speci- 

 mens may possibly merge it into the polymorphous S. Lecanium, 

 from the extreme variety of which the non-prominence of the 

 canal appears to separate it. Mr. Cuming's specimen measures 

 long. '83, lat. '57, alt. '3. 

 Hob. Gulf of California, Lieut. Shipley. Mazatlan ; 1 sp. 



only ; L'pool Col. 



Tablet 866 contains the specimen. 



241. SIPHON AEI A sp. ind. 



Tablet 867 contains a very young specimen, * 07 by "05, of 

 Navicella shape, with a large spiral apex, extremely thin, and 

 evidently belonging to a very much larger species than S. 

 Lecanium, possibly to S. gigas. 

 Hab Mazatlan ; 1 sp. in shell washings ; L'pool Col. 



