4 
184, MAZATLAN UNIVALVES 
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.—861, 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 8S. equilirata. Principal ribs scarcely traceable. 
240. SIPHONARIA EQUILIRATA, 7. S. 
S. t. subconicd, ovali, regulari, liris numerosis subrugulosis, 
equalibus, radiatim ornatd, interstitiis haud latis, levibus ; 
Fusco-olivaceda, liris altis ; epidermide tenui, adherente ; pagina 
interna fusca, vix iridescente; margine crenulato ; canali sub- 
centrali, extus haud prominente. 
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. Riblets 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 striule. The examination of more speci- 
mens may possibly merge it into the polymorphous 8. Lecanium, 
from the extreme variety of which the non-prominence of the 
canal appears to separate it. Mr. Cuming’s specimen measures 
jong. “88, lat.°57, alt. °3. 
Hab—Gulf of California, Lveut. Shipley —Mazatlan; 1 sp. 
only ; L’pool Col. 
Tablet 866 contains the specimen. 
241. SrFHONARIA ————— sp. tnd. 
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 §, 
Lecanium, possibly to S. gigas. 
Hab.—Mazatlan ; 1 sp. in shell washings; LZ’pool Col. 
