Zoological Society, 359 



interesting. Tlie posterior side of the shell is radiated with lines of 

 fine dark hair rising from between the crenulations of about every 

 third rib. 



Arca symmetrica. Area testa subquadratd, gihbosd, laterihus 

 superne acute angulatis, antico infra rotundato, postieo angulato ; 

 viridescente ; striis longitudinalihus et radiantibus crenulato-decuS' 

 satd ; ligamenti ared latiusculd, ligamento parvo, centrali. 

 Conch. Icon. Area, pi. 17. f. 117. 



Hab. Philippine Islands, bay of Manila ; Singapore (found under 

 stones at low water) ; Cuming. 



The ligament of this species occupies only a very small diamond- 

 shaped space between the umbones. 



Arca sculptilis. Arca testd oblongo-quadratd, lateribus superne 

 angulatis, infra obtuso-rotundatis ; albd; striis longitudinalihus et 

 radiantibus elevatis subtilissime clathratd ; ligamenti ared latius- 

 culd. 

 Conch. Icon. Arca, pi. 17. f. 118. 



Hab. Baclayon, island of Bohol, Philippines (found in sandy mud 

 at the depth of seventeen fathoms) ; Cuming. 



The engraved sculpture of this shell is of a more prominent cha- 

 racter than that of the preceding species. 



Arca zebuensis. Arca testd subquadratd, gibbosd, lateribus su- 

 perne angulatis, infra obliqu^ rotundatis ; fuscescente, epidermide 

 molli indutd ; radiatim subtilissime striatd ; ligamenti ared latius- 

 culd, ligamento parvo, centrali. 

 Conch. Icon. Arca, pi. 17. f. 120. 



Hab. Island of Zebu, Philippines (found under stones at low 

 water) ; Cuming. 



The ligament, as in the Arca symmetrica, occupies merely a small 

 diamond-shaped space between the umbones. 



Arca striata. Arca testd subquadrato-oblongd, lateribus obtuse 

 rotundatis ; fuscescente, epidermide molli indutd ; radiatim striatd, 

 striis elevatis, confertis, posticis distantioribus ; ligamenti ared 

 latiusculd, declivi. 

 Conch. Icon. Arca, pi. 17. f. 121. 



Hab. } 



This shell approaches very nearly to the Arca lactea, but it is yet 

 distinct ; the posterior side is longer, it is a more compressed shell, 

 and the posterior strise are more widely spread. 



Arca pulchella. Arca testd ovatd, gibbosd, lateribus supernh 

 attenuatis, antico brevissimo ; albd ; laminis longitudinalibus pro- 

 minentibus, pulcherrime fimbriatis, ornatd ; ligamenti ared antic^ 

 latiusculd ; umbonibus anticis. 



Conch. Icon. Arca, pi. 17. f. 122. 



Hab. Algeria. 



This species is well distinguished from any yet described by the 

 very beautifully fimbriated longitudinal laminae. 



