200 MR. J. W. KIRKBY ON ROME 



suture, and straight columella, pronounce it to belong to this 

 genus. The whole habit of the shell, too, is very similar to that 

 of Chemnitzia* 



3. Chiton Howseanus, s/?. nov. PI. XII. figs. 9-13. 



Three plates of a Chiton have occurred at Tunstall Hill,^^^^ich, 

 on a careful examination, appear to be distinct from Chiton Loftu- 

 siamiSj King (Monog. Perm. Foss. p. 202. pi. IG. figs. 9-14), of 

 which I have a full series. 



Of the new sj^ecies two of the plates are intermediate (figs. 10, 

 11, 12), and one anterior (fig. 13). The former plates are not 

 much compressed; they are wide and obtusely angulated, not 

 much pointed posteriorly, and they have a surface finely granu- 

 lated ; the lateral areas, which are rather wide, are not strongly 

 marked, and the lines of growth are indistinct; one or two wide 

 grooved lines, commencing at the posterior margin, run parallel 

 to the lower margin, and are continued faintly to the anterior 

 dorsal region. The anterior plate (fig. 13) is marked in a simi- 

 lar manner. The processes for insertion are more prominent, 

 narrower, and not so regularly arched as the apophyses of C. 

 Loftusianus (fig. 9). 



C. Howseanus may be readily distinguished from the last-named 

 ■species, which is the only other Chiton found in the Permian 

 rocks, by the flatness and greater width of the plates, by the 

 obscurity of the lateral areas, and smoothness (want of strong 

 lines of growth) of the plates. The one or two grooved lines 

 wdiich follow the margin are also characteristic. 



I have great pleasure in dedicating this species to Mr. R. 

 Howse, the author of an excellent " Catalogue of the Fossils of 

 the Permian System of the Counties of Northumberland and 

 Durham," and ''Notes on the Permian System of Durham," &c.f 



4. Lima Permiana. 



Lima Permiana, King, Monog. Perm. Foss. 154.^;/. 13. Jig. 4. 

 It may be interesting to mention that this species, which Pro- 

 fessor King founded upon the knowledge of a single valve from 



* See Note 2. t Sec Nute 3. 



