830 PELECYPODA. \Prolobranch\a. 



Genus 1. SOLEMYA, Lamarck, 1818. 



Solemya, Lamarck, A.s.V., v, 1818, 488. Type : S. australis, Lamarck. 

 Solenomya. Stephanopus, Scacchi, 1833. 



Shell equivalve, elongated, cylindrical, gaping at both extremities, 

 very inequilateral, thin, with a horny epidermis extending beyond 

 the margins, polished, and minutely punctured ; beaks posterior, 

 low ; hinge without teeth ; ligament partly internal. 



Distribution. Mediterranean, east coast of North America, Antilles, 

 Patagonia, Australasia ; also tropical, abysmal. 



Carboniferous to Recent. 



The foot can be extended to a sharp point or to a star- shaped 

 disc. The animals burrow in sand to a depth of 50 cm., but have 

 also been observed leaping or swimming about in the water for some 

 time without touching the bottom. 



1. Solemya Parkinsoni, E. A. Smith, 1874. Plate 58, fig. 1. 



Solemya Parkinsoni, Smith, Ereb. & Ter., 6, pi. 3, f. 1. S. australis, Lamarck : 

 Reeve, Conch. Icon., xx, 1875, f. 4 ; not of Lamarck. S. Parkinsoni, 

 Smith, M.N.Z.M., 157 ; Button, P.L.S. N.S.W., ix, 526. Solenomya 

 Parkinsoni, Smith, Index, 95. 



Shell moderate in size, equivalve, very inequilateral, with flat 

 radiate ribs, dark brown, polished, epidermis extending far beyond 

 the margin of the valves. Beaks very low, inconspicuous, at about 

 the posterior third of length. Anterior end broadly rounded, dorsal 

 margin straight ; posterior end roundly angled at the middle ; basal 

 margin straight, parallel to the dorsal. Sculpture consisting of very 

 low broad and flat ribs radiating from the Leaks toward the maigins, 

 the interstices slightlv concave. Epidermis polished, brown, horny, 

 exceeding the valves, usually slit at the termination of a rib. Colour 

 brown, the posterior part usually of lighter colour, with concentiic 

 and radiate darker bands ; interior greyish-Avhite, not iridescent. 

 Margins inside thin and sharp. Hhtr/c without teeth, a dental callo- 

 sity acutely produced toward the posterior side of the valve, margin- 

 ing the upper part of the posterior adductor scar, and a stout callous 

 rib running obliquely from the beak in fiont of the adductor-scar 

 toward the posterior margin. Ligament . amphidetic, parivincular, 

 internal posteriorly, rather narrow ; anterior part extended as a 

 narrow ridge, posterior part forming a thickened prop. Posterior 

 muscular scar not very large, triangular ; anterior scar large, tri- 

 angular, rounded in front. An indistinct pallial line, concave at the 

 middle, is mostly present. 



Length, 51 mm. ; height, 18 mm. ; diameter, 14 mm. (large spcci- 

 m n). 



Type in the British Museum. 



Hab. Throughout New Zealand, in fat mud about 6 in. below 

 the surface, often washed up after gales ; Kermadec Islands (Captain 

 Bollons) ; Milford Sound, in 100-120 fathoms (Professor Chilton). 



