858 PELECYPODA. [Filibrnttchici. 



of the umbo, the greater part of it internal, but distinctly visible from 

 the outside. Adductor-scar distinct, small and round, posterior. Pal- 

 lial line simple, not very distinct. 



Diameter Ant.-post., 2-5 mm. ; dorso-ventral, 3-2 mm. : thick- 

 ness, 2-2 mm. : prodissoconch, 0-35 mm. (type). 



Type in the Mus. Hist. Nat., Paris. 



Hab. Stewart Island, in 35 fathoms, type (Filhol) ; Whangaroa 

 Harbour (C. Traill) ; Lyttelton Harbour ; Otago Peninsula (T. Ire- 

 dale) ; Taumaki Island, in 10 fathoms (Captain Bollons) ; Foveaux 

 Strait, in 15 fathoms (A. Hamilton) ; north-east of Wreck Reef, in 

 50 fathoms, and off south-east of Cape Saunders, in 100 fathoms 

 (E. R. Waite) ; near the Snares and the Bounty Islands, in 50 fathoms 

 (Captain Bollons). 



In the littoral zone the shell may be found under stones and on sea- 

 weeds. 



Remarks. The species is variable in form, the anterior end some- 

 times descending almost vertically, and the posterior side being more 

 or less produced. 



The Pliocene P. trigonopsis, Hutton (Mytilicardia), is very nearly 

 allied, but the riblets are finer and more distant, and they are lacking 

 the median groove. 



2. Philobrya Filholi, Bernard, 1897. Plate 51, figs. 14, 14a. 



Philobrya Filholi, Bernard, J. de Conch., xlv, 1897, 16; 13, f. 2, 1; pi 1 

 f. 6. 



Shell small, solid, equivalve, inequilateral, subquadrangular, slightly 

 ventricose, with distant radiate riblets. Beaks close together, with 

 distinct flat prodissoconch, inclined towards the inner and posterior 

 sides, with an elevated convex rim on the outer side, and the centre 

 convexly raised. Anterior end slightly convex or straight, forming 

 an angle of 90 with the dorsal margin, which is straight or slightly 

 concave. Posterior end slightly convex or straight, forming an obtuse 

 angle with the dorsal margin ; basal margin convex. Lunular area 

 cordiform, flat, with concentric riblets. Posterior part oj m-i-n strongly 

 keeled. Sculpture consisting of 10 distant radiate riblets, which are 

 carinated, the interstices between them much broader than the costte ; 

 there are regularly spaced concentric cords, which are very distinct in 

 the interstices, but only feebly imbricating the riblets. Epidermis 

 slightly produced at the margins of the valves. Colour light-brownish 

 or yellowish-white. Interior light brown, rayed with whitish above, 

 smooth. Basal -wary in denticulate and finely crenulate. Hinge-plate 

 narrow, with a short oval anterior and a low elongate posterior ver- 

 tically crenate area. Ligament internal, triangular, long. Adductor- 

 scar round, small, posterior. 



Diameter Ant.-post., 2-5 mm. ; dorso-ventral, 3-2 mm. : thick- 

 ness, 2-2 mm. : prodissoconch, 0-35 mm. (type). 



