MAZATLAN BIVALVES 27 
Famity SOLECURTID. 
Genus SOLECURTUS, Blainv. 
37. SoLEcURTUS AFFINIS, C. B. Ad. 
O. B. Ad. Pan. Shells, p. 300, no. 510. 
The author of this species does not point out wherein it dif- 
fers from its Atlantic analogue, S. Caribeeus. The similarities are 
evident. 
The smallest specimen measures long. °3, lat. °84, alt. °14, 
The largest BX o ST RaENLy a pussies a Ae: 
HTab.— Panama, very rare, C. B. Ad.—Mazatlan: not common : 
TP’pool Col. 
Tablet 86 contains 4 young specimens.—87, 3 adult.—88, 3. 
lighter colour.—89, 3 with thinner epidermis.* : 
38. SOLECURTUS POLITUS, 1%. s. 
S. t. formd “S. affini” simili, sed subtranslucidd, violaced, extus 
lined fusca et lineis albicantibus nonniullis radiatd ; epider - 
mide politissimd, fusco-rubente : intus nymphis elongatis, 
denticulis 1-2 acutis, sinu pallii versus umbones maxime arcuato ; 
callositate ab umbonibus, lined fuscd exteriore con- 
veniente, subexpressi decurrente. 
Known at once by the brownish violet colour, glossy epider- 
mis, and dark ray corresponding with a slightly prominent 
ridge within. In this respect alone it resembles Machera. In 
the pallial sinus, S. aftinis is intermediate between politus and 
violascens: in colour, S. violascens is intermediate : in the pro- 
longation of the nympha, S. politus. This species displays 2 
small distinct muscular impressions between the umbo and the 
anterior adductor, which is oblong, but well defined : in S. vio- 
lascens, it tapers off irregularly, uniting with these two: in S. 
affinis it is irregular, not tapering, uniting with the others which 
are also irregular. The largest specimen measures long. °48, 
lat. 1°45. alé..” 23. 
Hab.—Mazatlan: 4 specimens found with affinis: L’pool Col. 
Tablet 90 contains the most characteristic specimen. 
* Lower down the coast was found a large specimen which appears a distinct 
epenee and I therefore append a description, and deposit the shell in the B. M. 
Cc 
SoLECURTUS VIOLASCENS. S, t. **S.affini” simili, sed majore, solida, violas- 
eeunte, rugis epidermidis tenuioribus ; nymphis elongatis, sinu pallii versus um- 
bones minus arcuato. Long °95, lat. 3° 33, alt. °56.—Hab. 8. W. Mexico, P. P. C. 
