304 BE. G. S. BEADT ON ENTOMOSTEAOA 



and evenly rounded, posterior attenuated and subacuminate ; 

 dorsal margin strongly arched and almost angular at its highest 

 point, thence sloping evenly and with a steep curve in both 

 directions, ventral slightly sinuated : seen from above, the out- 

 line is obovate, twice and a half as long as broad, broadest near 

 the front, extremities obtusely pointed. Surface of the valves 

 smooth and shining, milk-white, bearing numerous short, rigid, 

 hair-like papillae evenly distributed over the whole shell. Length 

 ■Jg. of an inch ('QQ millim.). 



One specimen only seen. 



This species is very like P. trigonella, Sars, but is smaller, 

 higher in proportion to its length, and more attenuated behind, 

 while the surface is more polished, and instead of adpressed hairs 

 has numerous minute processes of the true nature of which I am 

 not quite certain, as they assume different appearances under 

 different conditions of illumination ; I think, however, that they 

 are very minute setae. P. Davisoni, Brady, is also nearly allied, 

 but is more tumid and generally rounder in its outlines, besides 

 being destitute of any special surface-ornament. 



Genus Bairdia, M'Ooy. 



Baiedia teneea, n. sp. (Plate XXXIX. figs. 13-15.) 

 Shell, seen laterally, subreniform, highest in the middle ; height 

 equal to fully half the length ; anterior extremity obliquely 

 rounded, posterior produced into a not very prominent rounded 

 beak ; dorsal margin boldly and evenly arched, ventral sinuated 

 in the middle : seen from above, compressed, lozenge-shaped, 

 nearly thrice as long as broad, widest in the middle, thence taper- 

 ing evenly to the extremities, which are subacuminate. Surface 

 smooth, slightly granular, and bearing a few excessively short 

 hairs. Length -^ of an inch ('75 millim.). 



One specimen only was seen. The specimen has the appearance 

 of an adult shell, but it is nevertheless quite possible that it 

 may not be fully grown. Even so it can scarcely be referable 

 to any described species. 



Genus Aglaia, 0. S. Brady. 

 Aglaia (?) ACUMINATA, u. sp. (Plate XL. figs. 1-3.) 

 Shell elongated, compressed, reniform, higher behind than in 

 front : seen from the side it is nearly thrice as long as broad ; 



