1002 PELECYPODA. [Eulamfllibrftnchia. 



Genus 1. PSAMMOBIA (Lam.), Bowdich, 1822. 



Psammobia, Lamarck, A.s.V., v, 1818, 511 ; Bowdich, Elem. Conch., ii, 

 1822, 6, pi. 1, f. 10. Type : P. feroensis, Grnelin. Gari, Schumacher, 

 1817 (in part). Haplomochlia, Gistel, 1848. 



Animal with very long and slender siphons, longitudinally cib'ated, 

 the orifices papillose ; foot large, linguiform, and pointed ; palpi long 

 and subulate ; gills unequal, the outer smaller than the inner. Ana- 

 tomy of P. pattida : S. P. Woodward, A.M.N.H. (2), xv, 1855, 99, 

 with figs. 



Shell trans versety elongated, subequilateral ; anterior margin 

 rounded ; posterior margin usually subtruncate and angulate ; normal 

 formula of teeth- right valve with 2, left valve with 3 cardinals, but 

 this is almost always reduced until the left valve may have but 2 and 

 the right 1 tooth. Pallial sinus large. 



Distribution. About 100 species from all seas are known, from 

 below low-water mark to about 50 fathoms. 



Fossil in the Tertiary. 



Vernacular Name. Sunset-shell. 



KEY TO SUBGENERA. 



A. Shell elongated, compressed, pointed behind, posterior 



dorsal area more or less denned . . . . . . PSAMMOBIA, s. str. 



B. Shell blunt in form, inflated, truncate behind, posterior 



dorsal area not circumscribed . . . . . . GOBR^ITJS. 



Subgen. 1. PSAMMOBIA, s. str. 



Shell elongated, more or less pointed behind, compressed, some- 

 what rudely concentrically sculptured, the posterior dorsal area fre- 

 quently sculptured diversely from the disc, the pallial sinus elongated 

 and for the most part coalescent below with the pallial line. 



1. Psammobia lineolata, Gray, 1835. Plate 61, fig. 8. 



Psammobia lineolata, Gray. Yate N.Z., 309 ; Dieff. N.Z., 253 ; Hanley, 

 Cat. Rec. Biv. Shells, 59. 346, pi. 14, f. 1 ; C.M.M., 66 ; Grit, List, 42 ; 

 Conch. Icon., x, f. 58; Ereb. & Ter., 5, pi. 2, f. 11; M.N.Z.M., 142 ; 

 Hutton, P.L.S. N.S.W., ix, 520 ; Chall. Rep., xiii, 92. P. convexa, 

 Reeve, Conch. Icon., x, f. 59. 



Shell oblong, transverse, compressed, subequi lateral, thin, smooth, 

 shining, concentrically banded with purplish-pink and radially rayed 

 with white. Beaks approximate, not raised, small and inconspicuous. 

 Anterior end very little shorter than the posterior, narrowly rounded, 

 the dorsal margin almost straight, very little descending ; posterior 

 end bluntly angled a little below the middle, convexly ascending 

 towards the straight dorsal margin ; ventral margin very broadly 

 rounded. Lumilar area narrowly excavated. Posterior dorsal area 

 bounded by a ridge descending from the umbones towards the posterior 

 angle. Sculpture consisting of irregular fine concentric lines, more 



