ANIMALS. 117 



of Lepteenttf which may be regarded as only diflfering from the marginal expansions of 

 Camarophoria in their direction, being turned upwards, considering the perforate 

 valve to be the inferior one. Perhaps, as is the case with the geniculated portions 

 of Leptana, the marginal expansions constitute one of the generic characters of 

 Camarophoria : this is a point to which 1 may be allowed to draw the attention of 

 those who have an opportunity of fully studying the characters of the Carboniferous 

 HypotTiyridcB. 



The histology of Camarophoria agrees with that of Hypothyris. The valves 

 consist of closely-packed, capillary fibres, which pass through them at a very slight 

 angle, following, at the same time, a radiate arrangement as they succeed each 

 other from the umbones to the margins. The punctures are extremely minute, 

 and appear to intersect the fibrous tissue nearly at a right angle to the surface of the 

 valves. 



Camarophoria, in the apophysis of its large valve, undoubtedly possesses a striking 

 resemblance to Pentamerus ; and as it appears to have succeeded the latter genus in 

 time, I am disposed to regard both as being proximately related to each other. All 

 that prevents my arriving at a positive conclusion on this point, is the dissimilarity 

 existing between the apophysary system of their small valve ; which, in Pentamerm 

 consists of the two socket plates largely developed, and passing to a considerable distance 

 into the cavity of the shell ; whereas in Camarophoria it appears to consist of the medio- 

 longitudinal plate equally as much developed, and expanded bilaterally at its free or 

 upper margin. Perhaps a knowledge of the internal structure of some of the Penta- 

 meri described and figured by M. J. Barrande, in his paper ' Ueber die Brachiopoden 

 des silurischen Schichten vonBohmen,' 1847, may destroy the dissimilarity just noticed 

 by displaying the two plates of Pentamerm becoming gradually modified into the 

 spatula-shaped process of Camarophoria} 



Although related to Pentamerm, Camarophoria is also closely allied to Hypothyris, — 

 especially in form ; the only difference is in their internal structures, — Hypothyris having 

 the dental plates completely separated and divaricating, as in Orthis, which is well 

 displayed in several casts before me of Hypothyris pleurodon, and some other species. 

 The same amount of dissimilitude prevails between the apophysary system belonging 

 to the small valve of both genera : in Hypothyris it simply consists of the homologues 

 of the crura of the loop starting from within the socket plates, which are rarely 

 developed to any extent, offering in this respect a striking contrast with the large size 

 of the corresponding structures of Pentamerm. 



Concluding from what is at present known, Camarophoria does not appear to have 

 been numerous in species, nor to have had much chronological range. About half a 



^ Some of the so-called Spirifers figured by Kutorga in plate v of bis paper entitled 'Beitrag zur 

 Palaeontologie Russlands,' may throw some light on the affinity existing between Camarophoria and Pen- 

 tamerus. 



