31 



PRODUCTUS hemisphsericus. 

 TAB. CCCXXVIII. 



Spec. Char. Hemispherical, longitudinally 

 striated ; stria? fine ; lower valve very con- 

 cave. 



This Productus appears to be quite free from spines : 

 it is much wider than long, and has a straight back as 

 lono- nearly as the shell is wide : there is but a small 

 space between the valves for the animal, because the 

 lower one is very concave : the sides are slightly corru- 

 gated, otherways the general contour is characteristically 



regular. 



The larger specimen is from some part of Wales, by 

 favour of my kind friend Dr. Williams, Reg. Prof, and 

 the others from Mynidd Careg, near Kidwelly, in Car- 

 marthenshire, through the kindness of Mr. Richard 

 Taylor. They are both from Mountain Limestone, as I 

 beUeve the whole genus is. 



PRODUCTUS comoides. 

 TAB. CCCXXIX. 



Spec. Char. Semicircular, gibbose, very finely 

 striated ; disk inflated ; back staight, ex- 

 tending the whole width of the shell. 



The fineness of the striae, and form of this shell toge- 

 ther, give it the contour of a smoothly combed head of 



