548 PK0CEED1NG9 OF THE GEOLOGICAL SOCIETY. 



small ; volutions four ; upper part of the last whorl flattened, crossed 

 by large, rounded, oblique costse, which continue on the margin of 

 the whorl to its base. 



The costse are crossed by transverse, rounded striae, which, on the 

 convex margin of the large whorl, are about thirty in number, 

 becoming closer at the base. Aperture large, subquadrate. Speci- 

 mens of this genus are abundant in the Brocastle Liassic conglo- 

 merate, but they present so much variety, probably owing to age 

 and the condition of the test, that it is with much difficulty I can 

 arrive at specific distinctions. Examples in their young state, with 

 the exception of a few longitudinal costse, are quite smooth, whilst 

 others are highly ornamented. 



40. Neritopsis can-cellatus, spec. nov. PI. XY. fig. 20. 



Shell ovately globose ; spire small ; apex rather acute ; whorls 

 four; upper area of the whorls angulated, and crossed by acute 

 longitudinal costse, which, on the side of the body- whorl, are 

 decussated by coarse encircling striae, which become nodulated at 

 their junction. Aperture rather ovate. 



This species is more globose than If. exigua, and by its less nu- 

 merous and coarser costae may readily be distinguished from it. 



Log. The coralliferous conglomerate of Brocastle. 



41. Patella orn-ata, spec. nov. PI. XY. fig. 13. 



■Shell rather small, ovate, conical ; apex acute, slightly anterior 

 to the centre; anterior and posterior margins rounded; sides 

 flattened and more compressed; surface ornamented by rather 

 widely separated, somewhat irregular radiating ribs, which are less 

 prominent on the sides; these are decussated by numerous fine 

 lines of growth, which, wliere they cross the ribs, particularly 

 towards the margin, give them a nodulated appearance. 

 - This pretty species is found in the coralliferous conglomerate of 

 Brocastle and in the Sutton Stone at Sutton. At Brocastle it is 

 accompanied by P. Schmidti, Terq., and at Sutton by that shell and 

 P. JDunJceri, Terq. This species is rare, and does not attain the size 

 of those mentioned. Owing to an accident to a perfect example, I am 

 unable to give a better figure. 



42. Planoebis Mendipensis, spec. nov. PI. XY. fig. 10. 



Shell minute, discoidal, depressed; spire obtuse; volutions 

 nearly horizontal, increasing rather rapidly, divided by a canalicu- 

 lated suture, and slightly angulated. 



I possess but one specimen of this shell, which is from the base 

 of the Charter-House Liassic lead-mine, and is found in association 

 with the other terrestrial and marine remains which I have shown 

 to have been introduced therein. It is obvious that the ancient 

 freshwater species, for the first time discovered, owe their presence 

 in the mineral veins to the connexion of the latter T\ath freshwater 

 streams or lakes of the Liassic period. Tn the Charter-House mine 

 individual specimens are very rare. I shall, on another occasion, 



