PSAMM0D0XTID2E. 
105 
Psammodus expanses (Davis). 
1884. Astrabodus expansus , J. W. Davis, Quart. Journ. Geol. Soc. 
Yol. xl. p. 630, pi. xxvi. figs. 11, 12. 
Type. Imperfect teeth ; Horne Coll., York Museum. 
Teeth somewhat saddle-shaped, broader than long. Year the 
outer lateral margin the crown is raised into a prominent ridge, 
which extends backwards as a process beyond the remainder of the 
posterior border. 
Form. Sf Loc. Upper Carboniferous Limestone (Yoredale Docks): 
Yorkshire. 
P. 4903. Fragmentary abraded tooth; Wensleydale. Horne Coll. 
Psammodus salopiensis, sp. nov. 
1862. A palate, or part of a palate, Morris & Roberts, Quart. Journ. 
Geol. Soc. yoI. xYiii. p. 10-5, pi. iii. fig. 5. 
Type. Four associated teeth, in natural relative positions; British 
Museum. 
A small species. Teeth comparatively thick; the inner two 
thirds of the crown round and tumid, rapidly thinning outwards 
laterally. 
Form. Sf Log . Carboniferous Limestone (zone of Rhynchonella 
pleuroclon) : Fallow, Shropshire. 
36469. Type specimen, figured, of the natural size, by Morris and 
Roberts, loc. cit. Two symmetrical pairs of teeth are 
shown, one behind the other. Of one pair each tooth is 
approximately as broad as long, while of the succeeding 
(or preceding) pair the length equals only about two 
thirds of the breadth. The appearance of tapering both 
anteriorly and posteriorly is due to accidental fracture. 
Presented by G. E. Roberts , Esq., 1862. 
Psammodus trapesiformis (Davis). 
1883. Homalodus trapeziformis, J. W. Davis, Trans. Roy. Dublin Soc. 
[2] vol. i. p. 482, pi. lviii. fig. 30. 
1883. Homalodus quadratus , J.W. Davis, tom. cit. p. 482, pi. lviii. fig. 31. 
Type. Detached tooth ; British Museum. 
The teeth are comparatively thin, though the root attains about 
twice the thickness of the crown ; the coronal surface seems to have 
been flat, smooth, and punctate. The length and breadth of each 
