358 Zoological Society. 



Conch. Icon. Area, pi. 16. f. 110. 

 Hab. ? 



The sculpture of this shell is of the most exquisite description, 

 and reminds one forcibly of the delicate embossed carving of the 

 Chinese. 



Arca cojieta. Area iestd eJongatd, latere antico brevissimo, at' 

 tenuato, rotundato, postieo longissimo, plano-anguhito ; albidd ; 

 radiatim striatd, striis elevatis, posticis latioribus, prominentibus, 

 dislantioribus, siibsquamosis ; umbonibus anticc adjectis ; Vigamenti 

 area angustd. 



Conch. Icon. Area, pi. 16. f. 111. 



Hab. Sorsogon, island of Luzon, Philippines ; Cuming. 



The posterior striae acquire almost the importance of ribs. 



Arca olivacea. Arca testa ovato-qiiadratd, temticuld, suhcequi- 

 laterali, lateribus rotundatis ; albidd, ep'tdermide olivaceo-Jiiscd 

 tenui corned induid ; subtilisshne radiatim striatd, striis numerosis, 

 confertis ; ligamenti ared mediocri, umbonibus subcentralibus. 

 Conch. Icon. Arca, pi. 16. f. 113. 



Hab. San Nicolas, island of Zebu (found in sandy mud at the depth 

 of four fathoms) ; Cuming. 



This shell is not much unlike the Arca lactea in general appear- 

 ance ; it will be found, however, on examination to be a much thinner 

 and more delicate shell, whilst the umbones are sharper and more 

 closely approximated. 



Arca mixuta. Arca testd orbicidari-ovatd, subcequivahi, lateribus 

 superne angulatis, infra rotundatis ; albidd, subpellucidd, epider- 

 mide tenui moUi indutd ; radiatim striatd ; ligamenti ared latius- 

 culd, ligamento parvo, centrali. 

 Conch. Icon. Arca, pi. 17. f. 112. 



Hab. Philippine Islands (found in coarse sand at the dei)th of six 

 fathoms) ; Cuming. 



A very minute species, which cannot be referred to any hitherto 

 described. 



Arca navicella. Arca testd quadrato-elongatd, subcompressd, 

 lateribus superne angulatis, antico infra rotundato, postieo angu- 

 lato, carina ab umbone ad marginem decurrente ; radiatim striatd ; 

 albidd, fusco postice sparsim strigatd ; ligamenti ared elongatd. 



Conch. Icon. Arca, pi. 17. f. 114. 



Hub. Calapan, island of Mindoro, Philippines (found in coarse sand 

 at the depth of ten fathoms) ; Cuming. 



This is a little species of the Arca Noce or naviform group. 



Arca lateralis. Arca testd oblique trapezifonni, lateribus superne 

 angulatis, antico brevissimo, postieo latissimo. oblique expanso ; 

 radiatim costatd, costis 7iu}nerosis, angustis, crenaiis, epidermide 

 subpilosd indutd ; ligamenti ared pared . 



Conch. Icon. Arca, pi. 17. f. 115. 



Hab. Philippine Islands ; Cuming. 



The peculiarly oblique growth of this species renders it extremely 



