78 MAZATLAN BIVALVES 



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



T. granulata. Tbe largest measures long. 1'5, lat. 1"66, 



alt. 1-06. 



Hah.—W. Coast Mexico, Say— S. W. Mexico, P. P. C— 

 Mazatlan, 3 specunens Tritli T. bistrionica, L'jpool Col.— 

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

 Cuming.— EcudiAoY, St. Elena, D'O/'J/f/ny.— Panama, Jeicett, 

 (Gould ms.) — ? Do. : common, C. B. Adams. — Gu2ijTaa.s, 

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

 sandy mud, 11-13 fm. Cuming. 

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



Ill, Tapes squamosa, n. s. 



T. t. jparvd, subquadratd, ohlonga, alba fusco maculatd ; 

 margins dorsali suhrecto, postice angulato ; costis fortihus ah 

 umhone prominente radiaiitibus, liris concentricis parte anteriori 

 etvenirali decussatis ; parte posteriori liris obsoletis, costis 

 ibiinterruptis, squamosis, maxime casta lig amenta 

 proximd; dentihus 2-3 cardinalibus divergent ihus ; sinu 

 pallii subovali; lunula impressd. 



Remarkable for tbe strong radiating ribs, broken up into 

 scales posteriorly wbicb are very large on tbe 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. 'llS, alt. "OS. 

 _g-(j5,_]VIazatlan ; from -washings of Chamse and Spondyli ; 



extremely rare ; L'pool Col. 



Tablet 372 contains the only 3 valves found. 



Gentts AJJ^OMALOCAEDIA, Klein. 



Anomalocardia, Schum. 1817, Essai d'unc MWi. p. IZ^.—Besh. 



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

 Triquetra, Blainv. 1818. 

 Cytherea, sp. Lam. 

 Venus sp. Soiv. Phil. &c. 



This small group of Venerida^, consisting of species classed 

 sometimes ^\-ith Venus, sometimes with Cytherea, is weU char- 

 acterized by its irregular growth and extremely small paUial 

 sinus. 



