188 



striae than O. hyalinum. 0. Floridanum is more ventricose and much 

 more attenuated. 



Donax flexuosus. T. triangularis, cuneata undulato-flexuosa, 

 antice acuta, area postica lata, altii, subplanulata, undique striis exili- 

 bus profundis radiantibus insculpta ; apice post-mediano ; angulo um- 

 bonali postice carinato ; margine ventrali excurvata ; colore albo vel 

 stramineo, intus interdum postice violaceo. Long. 1 ; alt. £ ; lat. -| poll. 

 Inhabits Santa Barbara. Col. Jewell. 



Tellina tersa. T. modica, convexiuscula, ovato-triangularis, 

 alba, concentrice vix striata ; apice post-mediano ; extrem. antica 

 rotundata, superne compressa ; extrem. postica triangulari, apice sub- 

 acuto ; margine dorsali recta, cito desinente : dentibus lateralibus 

 obsoletis. Long. 1; alt. 3.7; lat. 0.3 poll. Inhabits Panama. Col. 

 Jewell. 



Generally resembles T. lineala Turt., but is smaller, more com- 

 pressed, and destitute of lateral teeth. Allied closely to T. plebeja, 

 but is more equilateral and quite white. 



Tellina pura. T. parva, sub-elliptica, vix inequilateralis, tenuis, 

 lucida, vel zonis lacteis zonata, striis minitissimis radiata ; apice acuto ; 

 extremitate antica semiovali ; extrem. postica modice angustata, trun- 

 cata, hiante, plica admodum conspicua ; intus nitida, striis elevatis 

 tenuibus radiata; dentibus lateralibus carentibus. Long. 1; lat. 0.3; 

 alt. 0.6 poll. Inhabits Panama, Col. Jewett ; San Diego, Lieut. Green. 



Remarkable for its symmetrical form and great simplicity. 



Tellina Gemma. T. parva, inequilateralis, transversa, ovato- 

 triangularis, striis rotundatis, concentricis ordinatis insculpta, rosea, 

 albido vix radiata ; extremitate antica semiovali, superne acute rotun- 

 data ; extrem. postica breviori, flexuosa sub-triangulari ; flexura valde 

 acuta ; margine ventrali postice incurva ; intus vivide rosacea. Long. 

 | ; alt. T 3 g ; lat. -^ poll. Inhabits San Juan. Lieut. Green. 



Resembles in form and color T. distorta and T. rhomboidea, and 

 more especially T. scalpellum. 



Cyrena altilis [is regarded as a variety of C. Mexicana]. 



Venus [Trigona] tantillus. T. parva, ovato-trigona, ventri- 

 cosa, inequilateralis, solidula ; levis vel sulculis remotis concentricis 

 arata, alba, postice fusco tincta ; margine dorsali postica longiori, 

 rectiuscula, angulo acuto. Long. \ ; alt. \ poll. Inhabits Santa Bar- 

 bara. Col. Jewett. 



This little Venus reminds one of V. geynma, or rather is like a min- 

 iature V. meretrix in form and coloration. 



