258 BIVALVE SHELLS. 



satis solida, transversim insequaliter tenuissime striata, epider- 

 mide fusco-vireseente, inferne lamellosa vestita; umbonibus 

 magnis, prominentibus, oppositis, decorticatis, approximatis, 

 latere antico brevi, late rotundato, postico attenuato, superne 

 declivi, extremitate truncato, angulo obtuso decurrente cir- 

 cumscripto ; cardine angusto, in medio paulo latiore ; dentibus 

 tribus primariis ina^qualibus approxiraatis angustis, apice pro- 

 funde biiidis, lateralibus magnis ffiquidistantibus, antieo paulo 

 majore, conico, acuto ; valvis intus candidissimis. 

 Cyrena (anomala) Cumingii, Desh. Proc. Zool. Soc. 1854. 

 Hab. America centralis. Coll. Cuming. 



52. Cyrena Isocardioides. 



C. testa orbiculato-subtrigona, insequilaterali, turgida, cordiformi, 

 tenui, fragili, tenuissime transversim inaequaliter striata, epi- 

 dermide olivaceo-nigrozonulata, vestita ; umbonibus magnis, 

 subinvolutis, oppositis, atro-violaceis ; latere antico regulariter 

 late semicirculari, postico superne declivi, attenuato, subros- 

 trato ; area plana, ovato-lanceolata, angulo lato obtuso de- 

 currente circumscripta ; cardine angustissimo, dentibus pri- 

 mariis tribus minutissimis, approximatis, subsequalibus, duobus 

 anticis parallelis, postico divaricato ; dentibus lateralibus mini- 

 mis, subaequidistantibus, margine sulco angusto profundo 

 separatis, in valva dextra duplicatis ; pallii impressione margine 

 inferiore proxima ; valvis intus albis, utroque latere violaceo 

 maculatis. 



Cyrena (anomala) Isocardioides, Desh. Proc. Zool. Soc. 1854. 



Hab. Columbia occidentalis. CoU. Cuming. 



53. Cybena maritima. 



C, testa orbiculato-cordiformi, subaequilaterali, turgida, tenui, 

 transversim irregulariter et dense striata, epidermide viridi- 

 fuscescente induta; vimbonibus magnis, parum obliquis, ap- 

 proximatis, acutis, Isevigatis, latere antico superne declivi, 

 convexiusculo, in medio parumper attenuato et obtuso, postico 

 breve truncato; area magna convexa, ovata, angulo obtuso 

 decurrente circumdata ; cardine angusto ; dentibus primariis 

 tribus, minimis, subaequalibus ap})roximatis, apice biiidis diver- 

 gentibus, lateralibus aequaliter remotis, in valva dextra du- 

 plicatis, antico usque ad cardinem canaliculato. 



Cyrena maritima, Adams, Panama Shells. 



Cyrena (anomala) maritima, Desh. Proc, Zool. Soc. 1854. 



Hab. Panama. Coll. Curaing. 



