38 SYRIAN MOLLTJSCAN FOSSILS. 



LAMELLIBRANCHIATA. 



Corbula aligera, sp. nov. 



Plate IV, Jigs. 6 a, b. c, d. 



Testa parva, triquetra, inceqiiUateralis, chum ; valcula dextra paulo major qiiam 

 sinisira ; postice ucuminuia, vukle unguUda ; margo anticus imimiatus el infra roiun- 

 datvs : umhones antemediani, superne appressi et obtusi, invohdi, antrorsinn iniorli : 

 superficies nigis sive vancibus conceniricis irregiduribus crassis induia : lunula infra 

 illimitata ; area cardinalis perangusta, lanceolata, tenidier excavata. Carina acida 

 alata, ab umbonibus ad icrniimdioncm postero-inferiorem rectc decurrens, aream pos- 

 iicam sidjconcavam costtdis radianiibus iiistructam a kdcribus diridd. 



Shell small, triangular, inequilateral, perfectly closed at the margins ; 

 right valve a little larger than the left, and tightly overlapping it ; pos- 

 teriorly acuminate, strongly angled ; anterior margin sinuated ahove and 

 rounded below : unibones a little in front of the middle point of the shell, 

 obtuse above as if pressed downward, involute and bent forward : surface 

 covered with thick, irregular concentric plaits, or varices : lunule undefined 

 below ; hinge ai-ea very narrow, lanceolate, slightly excavated. A sharp, 

 wing-like keel, running straight from the beaks to the postcro-inferior ex- 

 tremity, divides from the lateral surface the subconcave hinder area, which 

 is marked with radial rlblets. 



Three specimens. Length, 9 J mm. to lO^mm. ; height-, G mm. to 7 nun.; 

 thickness, inside of keels, 4 mm. to 5 mm. 



The concentric plaits are much narrower than the intervals which sepa- 

 rate them. They stop short upon the thin and elevated keel, and are wholly 

 distinct from the more numerous radiating riblets which adorn the nearly 

 flat posterior area. In these unusual features, the species approaches C. Val- 

 densis Hebert and Renevier "du Terrain Nummulitique superieur." (Fossiles 

 du Terrain Nummulitique superieur des Environs de Gap, des Diablerets, et 

 de quelques Localites de la Savoie. Grenoble, 1854, p. 50, PI. i, fig. 11.) 

 Coll. Bird. 



Locality and Position. — From arenaceous marl, probably Turonian and 

 from the vicinity of Abeih. 



