Mr. A. Adams on some new Mollusca. 307' 



Fig. 7. Cyathoseris magnifica : a, corallum, two-thirds the natural size ; 



b, cahce, magnified 2 diameters. 

 Fig. 8. Mycedium costatum : a, part of caUcular surface, natural size j. 



b, cahce, magnified 3 diameters. 



XXXI. — On some new Genera and Species of Mollmcafrom the 



Seas of China and Japan. By Arthur Adams, F.L.S. &c. 

 Already iu the ' Annals ' I have made known some conchiferous 

 Mollusks which I believe to be peculiar types of form with 

 which we have hitherto not been acquainted. Such, I conceive, 

 is Sarepta among Nuculidse, and Cyrilla, the aflfinities of which 

 seem to be with Zmojom. In this communication I have briefly 

 characterized two other forms which I am unable to refer to any 

 genera already established, — one of which appears to be allied to 

 Bucardia, and the other to Montacuta. The new species described 

 below are also of great interest on account of their beauty or 

 singularity of construction. 



Genus Callocardia, A, Adams. 



Testa cordata, tenuis, Isevis, inflata ; umbonibus parvis, subspirali- 

 bus, approximatis. Cardo (in valva sinistra) deutibus duobus in- 

 sequalibus, cum foveola angusta arcuata interposita, munitus ; dente 

 antico valde prominente, in medio angulatim flexo cum fossula antica 

 et postica instructo, margine quadricuspidato ; dente postico oblique, 

 arcuate, anguste, elongate, margine denticulis duebus vix elevatis 

 instructe ; dentibus lateralibus nullis. Pallii linea simplex ; impres- 

 sienes musculares semilunares. 



This genus is proposed for the reception of a beautiful shell, 

 of which, unfortunately, I possess but a single valve, which in 

 general appearance most nearly resembles a Bucardia. The 

 surface of the valve is simple, as in B. cor, but it is not covered 

 with an epidermis. The complicated nature of what I have 

 termed the anterior cardinal tooth, which is furnished with four 

 prominent cusps, and is angularly bent on itself in the middle, 

 with a triangular pit on each side, together with the absence 

 of lateral teeth, will distinguish Callocardia from the Isocardia 

 of Lamarck. The genus Anisocardia of M. Munier-Chalmas, 

 founded on a fossil shell from the Kimmeridge Clay of Havre, 

 appears to bear some resemblance to my proposed genus ; but 

 in that form the surface of the valves is radiately grooved, the 

 anterior muscular scar projects as in Cucullaa, and the disposi- 

 tion of the hinge-teeth seems to be very different. 



Callocardia guttata, A. Ad. 



C. testa cordata, inflata, laevi, nitida, alba, raaculis irregularibus 

 aurantiacis conspersis pulcherrime guttata, superficie lineis incre- 



