L88 



stria than 0. hyalinum. <>. Floridanum is more ventricose and much 

 more attenuated. 



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

 antice acuta, area postica lata, aha. subplanulata, UDdique striis exili- 

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

 bonab' postice carinato; margine ventrab* excurvata; colore albo vel 

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

 Inhabits Santa Barbara. Col. Jewett. 



Ti i.i i x \ 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 lateraHbus 

 obsoletis. Long. 1; alt.. - !. 7; lat. 0.3 poll. Inhabits Panama. Col. 

 J i wt tt. 



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

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

 but is more equilateral and quite white. 



Tellixa pura. T. parva, sub-elliptica, vix inequilateraUs, tenuis, 

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

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

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

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

 alt. 0.6 poll. Inhabits Panama, < 'ol. Jt wt tt ; San Diego, Lit ut. Green. 



Remarkable for its symmetrical form and great simplicity. 



Tin. una Gemma. T. parva, inequilateralis, transversa, ovato- 

 triangularis, striis rotundatis, concentricis ordinatis insculpta, rosea, 

 albido vix radiata; extremitate antica scmiovali. superne acute rotun- 

 data; extrem. postica breviori, flexuosa sub-triangular?; llexura valdc 

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



: alt. A ; lat. ^ poll. Inhabits San Juan. Lieut. Green. 

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

 more especially T. scdlpellum. 



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



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

 cosa, inequilateralis, sobdula; levis vel sulculis remotis concentricis 



arata. alba, postice fusco tincta; margine dorsali postica Iongiori, 

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

 bara. < 'ol. Jt wt tt. 



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

 iature V. meretrix in form and coloration. 



