Prof. W. King's Notes on Permian Fossils. 335 



possessing about the same number of ribs as the Russian type^ 

 have the entire umbonal region of both valves distinctly ribbed ; 

 besides,, the ribs appear to be more flattened. Moreover, I entertain 

 a suspicion that in the Russian shell the small valve is decidedly 

 more rounded posteriorly ; and I am also led to suspect that its 

 valves are not so obviously perforated, — a character which I think 

 could not have escaped the observation of M. de Verneuil or 

 Count Keyserling. However, for the present, I am content 

 with having simply pointed out what I consider to be some im- 

 portant differences, leaving it for others to confirm or overthrow 

 my suspicions. 



The Ropsen shell is subpentagonal ; and, compared with most 

 species of the genus, it may be said to have slightly convex 

 valves, both being only somewhat tumid posteriorly : the small 

 valve, however, has its anterior half rather strongly elevated, and 

 its sides sloping somewhat rapidly. The mesial sinus, or ridge, 

 terminates in front without giving any very abrupt wave to 

 the anterior margins : the wave is decided, but regular. The 

 ribs amount to about four or five in the sinus, and nine or 

 more on the lateral areas : they are broad, flat, evenly rounded, 

 and separated from each other by a narrow, line-like sulcation. 

 The rostral plates project forward about one-fourth the length of 

 the shell, with rather a strong divarication. The median plate 

 extends a little further along the small valve. The point of the 

 umbone is sharp and somewhat projecting ; and the foramen is 

 small. The perforations are large, and separated from each 

 other by an interspace about equaUing twice their own diameter : 

 they give the surface of the shell a finely granulated structure ; 

 and appear to decrease a little in size as they pass outwardly 

 through the capillary fibres, which are exceedingly fine*. This 

 interesting species has not yet been found out of Germany. 



* In my * Monograph ' it is stated, that I noticed the existence of perfo- 

 rations in every species of Rhynchonella, as well as other Brachiopods, that 

 had passed under my observation : hence I was led to make the statement 

 — " in short, I doubt their absence in any Brachiopod whatever " {op. cit. 

 p. 110, &c.). Dr. Carpenter, in his chapter " On the Intimate Structure of 

 the Shells of Brachiopoda," appended to Mr. Davidson's ' Monograph ' of 

 British fossil species of this Class, having deemed it necessarj- to anim- 

 advert somewhat strongly on the above piece of scepticism (vide op. cit. 

 pp. 31, 32 & 35 — notes), I have been induced to make the following ob- 

 servations : — Although Dr. Carpenter's researches, as detailed in his " Re- 

 port on the Microscopic Structure of Shells," published in the volume of 

 the British Association Meeting for 1844, were generally considered as lead- 

 ing to most important results ; yet it is well known that many regarded 

 them as too initiative to be unreservedly accepted in all their totality. Not 

 that Dr. Carpenter was in any respect to blame ; for it was conceived, that 

 fossihzation had so obliterated the tissue of many shells as to render a de- 

 tection of it an impossibility ; and it was also conceived that some shells 



