128 



Galeomma Turtoni. PI. 37. Fig. 200. Shell, with the valves closed to 

 show the gaping at the ventral margin. 



Genus 7. PSAMMOBIA, Lamarck. 



Animal ; oblong, compressed, its mantle open throughout and bor- 

 dered by a fringe of fine silken filaments ; siphons very long, 

 slender, and delicate, marked with longitudinal ciliated lines, 

 which terminate in more or less conspicuous cirrhi, few (six or 

 eight in number) surrounding their orifices. (Forbes.) 



Shell ; transversely oblong, moderately inequilateral, a little gaping 

 at the side, the posterior mostly fiexuously angled ; hinge com- 

 posed of two teeth in one valve, generally bifid, and one in the 

 other. 



To genus Psammobia is referred a series of sixty exquisitely beautiful 

 bivalves, confined, with one or two abnormal exceptions, to the Eastern 

 Hemisphere, ranging, but with comparative scarcity, from the Hebrides 

 to Tasmania, and represented on our own shores by the elegant P. vesper- 

 tina, Ferroensis, tellinella, and costulata. The animal, like Tellina, has 

 its siphonal tubes of unequal length, widely separated and extended, but 

 they are curiously fluted, so far as regards the British P. tellinella, with 

 six or eight ciliated lines, terminating at the margins of the orifices in 

 cirrhi. The shell presents more dainty varieties of radiated painting, simu- 

 lating the rays of the setting sun, than in any other genus of Nymphacea, 

 and there are more varieties of concentric striation. In many species the 

 raised striae are not parallel with the lines of growth, but cross them ob- 

 liquely, waving fiexuously on to the posterior beaked angle ; and in a few 

 of the smaller species the angle is carved with elaborately scaled ridges. 

 The Psammobia dwell in sand or gravelly mud, but are not of sluggish 

 habits. 



1. abrupta, Besh. 



2. affinis, Reeve. 



3. amethystus, Wood. 



4. amcena, Besh. 



5. angusta, id. 



6. anornala, id. 



7. bicarinata, id. 



Species. 



8. cserulescens, Lam. 



9. candidula, Besh. 



10. casta, Reeve. 



11. castrensis, Chemn. 



12. compta, Besh. 



13. convexa, Reeve. 



14. corrugata, Besh. 



15. costulata, Turt. 



16. denticulata, Ad. 8f R. 



17. dispar, Besh. 



18. eburnea, Reeve. 



19. elegans, Besh. 



20. Ferroensis, Chemn. 



21. grata, Besh. 



