158 Tlircc New Fossils 



the buckler ij prolonged, whilst in our species it is truncated. In 

 the Leucosis the posterior part is truncated, in this it is rounded. 

 The specimens which I have are the mere bucklers of the animals, 

 without logs, claws, branchiae, or antennae, and resemble the rejected 

 shells of ordinary Crustacea. There are on the crown or top of all 

 tho specimens, regularly waved lines or grooves; on each side of 

 the slope, corresponding to each other, in one specimen, these hnes 

 are dark-coloured ; in another the colour is faint, but the grooves 

 deeper and more distinct, and in the third, they are almost obso- 

 lete. The cavity on the under side of the buckler being entirely 

 filled with chrystaline lime-stone, prevents any description of that 

 part of the animal being made : length 0.9 inch, breadth 0.7 inch. 



GENUS PENTAGONIA. 



Shell bivalve, inequivalve, having five sides, somewhat gaping j; 

 lower valve with three sides, upper with two ; beaks contiguous. 



* P. Peers ii. 



Shell somewhat gaping, with five sides and tln-ee carinae y 

 two of the carinae on the lower valve commence at the beak, and 

 diverge towards the margin, and end at the opening, the valve be- 

 ing concave between them ; the lateral margins small and nearly 

 vertical, an elevated carina on the middle of the upper valve,' ren- 

 dering its sides somewhat concave. This carina has a shallow 

 furrow in it, commencing at the beak and running more than hair 

 way along the shell towards the opening. On each side of the up- 

 per valve and contiguous to the beaks, are two angular protuberan- 

 ces, giving the shell when viewed at the beaks, a pentagonal ap- 

 pearance, and at the same time a visage-form look: length 1.1 

 inch, breadth 0.0 inch. Plate X. fig. 2, a. b. 



The cavity of this shell was filled with the samo limestone as 

 the Piliolites. 



GENUS CONULITES. 



Shell pyramidal, somewhat quadrangular, with the planes some- 

 what curved, aperture wido and festooned by lines of growth. 



