A R C A. 



(Figures moderately magnified.) 



Species 112. (Mus. Cuming.) 

 Arca minuta. Arca testd orbiculari-ovatd, subepqui- 



valvi, lateribus superni angulatis, infra rotundatis ; 



albid/i, subpellucidd, epidermide tenui molli indutd ; 



radiatim striata ; ligamenti area latiusculd, ligamento 



parvo, centrali. 

 The minute Ark. Shell orbicularly ovate, nearly equi- 



valve, sides angular, rounded beneath ; whitish, 



somewhat transparent, covered with a thin soft 



epidermis ; radiately striated ; area of the ligament 



rather wide, ligament small, central. 

 Reeve, Pro. Zool. Soc, 1844. 

 Hab. Philippine Islands (found in coarse sand at the 



depth of six fathoms) ; Cuming. 

 A very minute species, which cannot be referred to 

 any hitherto described. 



Species 1 14. (Mus. Cuming.) 



Arca navicella. Area testa quadrato-elongatd, sub- 

 compressd, lateribus superne angulatis, antico infra ro- 

 tundata, postico anguhtto, carina ab umbone ad mur- 

 ginem deeurrente ; radiatim striatd ; albidd, fuseo 

 postice sparsim strigatd ; ligamenti ared elongatd. 



The little ship Ark. Shell squarely elongated, some- 

 what compressed, sides angulated at the upper part, 

 anterior rounded beneath, posterior angulated, with 

 a keel running from the umbone to the margin ; 

 radiately striated ; whitish, sparingly streaked at 

 the posterior end with brown ; area of the ligament 

 elongated. 



Reeve, Pro. Zool. Soc, 1844. 



Hab. Calipan, 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. _____ 



Species 115. (Mus. Cuming.) 



Arca lateralis. Arca testa oblique trapeziformi, late- 

 ribus superne angulatis, antico brevissimo, postico 

 latissimo, oblique expanse ; radiatim costatd, costis 

 numerosis, angustis, crenatis, epidermide subpilosd 

 indutd ; ligamenti ared parvd. 



The one-sideh Ark. Shell obliquely trapeziform, side* 

 angulated at the upper part, anterior very short, 

 posterior very wide, obliquely expanded ; radiately 

 ribbed, ribs numerous, narrow, crenated, covered 

 with a somewhat hairy epidermis ; area of the liga- 

 ment small. 



Reeve, Pro. Zool. Soc, 1844. 



Hab. Philippine Islands ; Cuming. 



The peculiarly oblique growth of this species renders 

 it extremely interesting. The posterior side of the 

 shell is radiated with lines of fine dark hair rising from 

 between the crenulations of about every third rib. 



Species 116. (Mus. Metcalfe.) 



Arca lactea. Arca testd subquadrato-ovali, lateribus su- 

 perne angulatis, antico infra obtuso-rotundato, postico 

 angulato-rotundato ; albidd, epidermide fuscescente 

 indutd; radiatim striata, striis e/eeatis, subtilissime 

 crenulatis. 



The milk-white Ark. Shell somewhat squarely oval, 

 sides angulated at the upper part, anterior obtuse- 

 ly rounded beneath, posterior angularly rounded ; 

 whitish, covered with a light brown epidermis ; 

 radiately striated, stria; raised, very finely crenu- 

 lated. 



Linn_tjs, Syst. Nat., p. 1141. 



Lamarck, Anim. sans vert. (Deshayes' edit.), vol. vi. 

 p. 4G7. 



Arca modiolus, Poli. 

 Arca Quoyi and Gaimardi ? Payrandeau. 



Hab. Mediten 



This species appears to have been described originally 

 from some specimens that had become bleached on the 

 shore, as it is not particularly white. 



Species 117. (Mus. Cuming.) 

 Arca symmetrica. Arca testa subquadratd, gibbosd, 

 lateribus superne acute angulatis, antico infra rotun- 

 dato, postico angulato ; viridescente; striis longitudi- 

 nalibus et radiantibus crenulato-decussatd ; ligamenti 

 area latiusculd, Ugamenlo parvo, centrali. 



