Limopsis.] PELECYPODA. 853 



Earn. LIMOPSID^, Ball. 



Animal with, the foot elongate, pointed anteriorly and posteriorly. 

 Shell suborbicular, the hinge curved, the ligament simple, small, 

 external or only partly so, interrupting the line of teeth, with the 

 transverse axis longer than the longitudinal. 



KEY TO GENERA. 



A. Shell with a hairy epidermis, beaks median, ligament external . . LIMOPSIS. 



B. Shell smooth or sculptured, beaks anterior, ligament internal . . LISSARCA. 



Genus 1. LIMOPSIS, Sasso, 1827. 



Limopsis, Sasso, Giorn. Ligust. Sci. Let. et Arti, Geneva, i, 1827, 476. Type : 

 Area aurita, Brocchi. Pectunculina, d'Orbigny, 1844. Trirjonoccelia, 

 Nyst et Galeotti, 1835. Felicia, Mabille et Rochebrune, 1889. Cos- 

 metopsis, Rovereto, 1898. 



Animal similar to that of Glycymeris ; foot with a longitudinal 

 groove and a much reduced byssus, with which the animal can fix 

 itself to submarine bodies. 



Shell ovato-rotund, slightly oblique behind, thick, with a hairy 

 epidermis ; umbones median, prominent ; area well marked but 

 narrow ; fossette of the ligament vertical, triangular, under the beaks ; 

 hinge-plate thick, broad, arched, with two series of teeth, their number 

 small ; the anterior adductor-scar frequently very small. 



Distribution. Australasia, Japan, west coast of Central America ; 

 Red Sea, European seas, &c. ; living at variable depths, also abysmal. 



Fossil. Trias to Tertiary. Two species are recorded from New 

 Zealand, one of which, L. Zitteli, von Ihering (= insolita, Hutton, 

 not of Sowerby) is nearly allied to L. insolita, Sowerby, of the Tertiary 

 of Patagonia. 



1. Limopsis lata, E. A. Smith, 1885. Plate 51, figs. 9, 9a. 

 Limopsis lata, Smith, Chall. Rep., xiii, 1885, 257, pi. 18, f. 7, la. 

 Shell moderately thick and ventricose, somewhat oblique, of a 

 dirty-whitish colour. The umbones are acute when not eroded at the 

 tips, as is frequently the case, and located a trifle in advance of the 

 middle. The anterior side is broadly curved and very oblique below 

 the middle, the posterior being less regularly arcuate and in some 

 examples somewhat truncated. The hinge margin is straight and 

 rather long. The sculpture consists of fine radiating and concentric 

 lirfe, producing a cancellated surface. Epidermis towards and upon 

 the outer margin rather coarsely fibrous. Colour dirty-white. In- 

 terior dull-whitish, rather roughish, exhibiting a kind of shallow 

 pitting or subpunctation. The outer margin is thickened, distinctly 

 dentate inferiorly, and crenulate at the sides. The hinge-teeth are 

 strongish, in an almost straight series, and number about 8 or 9, of 

 which 2 or 3 more are on the anterior side of the beaks than behind. 



