46 Mr. R. Howse on the Permian System of the 



ment of the muscles. The surface round about these muscles 

 and the cardinal regions is neatly pitted, causing small pimples 

 on the casts ; these are probably the ovarian spaces. One ob- 

 serves similar markings on the cori*espondiug parts of the other 

 valve. 



It is generally supposed that the reniform callosities are con- 

 nected with the vascular system, but this supposition appears to 

 be unsupported by a comparison of these processes with the cor- 

 responding parts of other Brachiopods. If we compare them, 

 for example, with the same valve of Argiope, or of Thecidium, 

 genera which show points of resemblance to this in several par- 

 ticulars, we find that these processes have served for the attach- 

 ment of the oral arms ; and this view is supported by all that we 

 know of the position of these arms in both recent and fossil 

 genera. At least, these structures cannot be attributed to the 

 vascular system, or they would undoubtedly be present in both 

 valves, whereas they are confined to one. 



On some casts of this Productus a great number of small 

 parallel grooves or furrows are seen running from the central 

 ovarian region to the anterior margins of the valves; they are 

 not very distinct, but they may perhaps hereafter be found to have 

 been connected with the vascular system. This idea is some- 

 what strengthened by the appearance of similar lines on some 

 casts of Spirifer, which few persons would hesitate to pronounce 

 as vascular sinuses. There remain to be noticed on this small 

 valve the curious spine-like callosities which stud the whole of 

 the anterior portion of the shell ; they are strongest where the 

 produced, curved-up portion of the margin takes its rise, and 

 seem to have been for the more secure attachment of the mantle 

 and for giving it a greater surface. 



In the lower valve an elevated callosity near the beak of the 

 shell forms a fulcrum for the attachment of the adductor muscles ; 

 its surface is strongly rugose. On each side of it are placed the 

 somewhat oblong, hnely-striated impressions of the cardinal 

 muscles. The small pittings on the ovarian regions, the spinose 

 callosities, and grooved surface of the interior correspond with 

 the same appearances in the upper valve. 



It is found in England in the compact- and shell-limestone 

 only, in numerous localities. 



4. Productus latirostratus, Howse. — When I was engaged 

 in drawing up my Catalogue of Permian Fossils, I found that 

 this shell had not been described or mentioned by any one ; and 

 as I had collected several fine specimens at Dalton-le-dale, and 

 had not seen or heard of any other specimens of it than these, 

 I concluded that it was entirely new, and described it as such in 

 the ' Tyneside Transactions ' as follows : — 



