MAZATLAN BIVALVES 



possibly a distinct species, and closely resembles the W. Indian 

 T. gramilata. The largest measures long. 1*5, lat. 1'66, 

 alt. 1'06. 



Hab.W. Coast Mexico, Say. S. W. Mexico, P. P. 0. 

 Mazatlan, 3 specimens with T. histrionica, L'pool Col. 

 (T. discors) St. Elena and Guacomayo, in sandy mud, 6-9 fm., 

 Cuming. Ecuador, St. Elena, D'Orbigny. Panama, Jewett, 

 (Gould ms.) ? Do. : common, C. B. Adams. Guaymas, 

 Lieut. Green, (Gould ms.). (T. tricolor) Puerto Portrero, in 

 sandy mud, 11-13 fm. Cuming. 

 Tablet 370 contains the small specimen ; and 371, the largest. 



111. TAPES SQUAMOSA, n. s. 



T. t. parvd, subquadratd, oblonffd, alba fusco maculatd ; 

 margine dorsali subrecto, postice angulato ; costis fortibus ab 

 umbone prominente radiantibus, liris concentricis parte anteriori 

 etvenlrali decussatis ; parte posteriori liris obsoletis, costis 

 ibi interruptis, squamosis , maxime costd lig amento 

 proximo, ; dentibus 2-3 cardinalibus divergentibus ; sinu 

 pallii subovali ; lunuld impressd. 



E,emarkable for the strong radiating ribs, broken up into 

 scales posteriorly which are very large on the rib next the 

 ligament. On the body of the shell these are decussated with 

 moderately distant raised concentric lines. The young shell 

 has in one valve a long posterior lateral tooth close to the liga- 

 ment. This shell measures long. '03, lat. *04; the largest valve 

 long. '09, lat. '115, alt. "05. 

 Sab. Mazatlan ; from washings of Chamse and Spondyli ; 



extremely rare ; Upool Col. 



Tablet 372 contains the only 3 valves found. 



GENUS ANOMALOCAEDIA, Klein. ' 



Anomalocardia, Sckum. 1817, Essai d'une Meth. p. 134. Desk. 



B. M. Cat. Yen. p. 115. 

 Triquetra, Blainv. 1818. 

 Cytherea, sp. Lam. 

 Venus sp. Sow. Phil. &c. 



This small group of Yeneridse, consisting of species classed 

 sometimes with Yenus, sometimes with Cytherea, is well char- 

 acterized by its irregular growth and extremely small pallia! 

 sinus. 



