114 PERMIAN FOSSILS. 



In a paper published by myself in 1844, I announced my intention of forming a 

 new genus, under the name of " Camerophoria, for a shell approximating to Pentamerus 

 in some points of its internal structure ;"^ but it was not until 1846 that an opportunity 

 occurred to me of entering into any description of its distinctive characters/ The 

 details then published have in general been confirmed by observations I have 

 recently made ; so that little is required at present but to transcribe them with such 

 alterations as are rendered necessary by the arrangements and modified nomenclature 

 adopted in this work. 



Describing from the type of the genus, and its ally Camarophoria muUiplicata, the 

 large valve possesses a fissure (PI. VII, fig. 13 a), which is open, and in general only 

 exposed in young individuals ; in old ones it becomes dilated at its base, and is then 

 occupied with the point of the umbone of the opposite valve, as in Pentamerus 

 {galeatui). The dental plates pass from thQ fissure, one on each side of it, to nearly a 

 third of the length of the shell (PI. VIII, figs. 3, 4 «) : they conjoin at their superior 

 margin, so as to form an arch-shaped process, the crest of which is attached to a 

 low vertical plate (evidently the homologue of what has elsewhere been termed 

 the ventral medio-longitudinal plate), which gradually becomes higher as it passes 

 from the apex of the fissure to the anterior part of the umbonal cavity (PI. VIII, 

 figs. 3, 4 3). The arch-shaped process, and its supporting or suspending plate, 

 correspond in every respect, except in degree, with the apophysary system belonging 

 to the large valve of Pentamerus. 



In the opposite or small valve, the space between the dental sockets is occupied 

 with a horizontal plate (PI. VIII, figs. 3, 5 c) attached on one side to the hinge, and 

 free on the other : its centre is occupied with a small protuberance marked with lines 

 or striae (PI. VIII, figs. 3, 4, h d). This plate is considered to be the equivalent of 

 the crural base, and the protuberance, the counterpart of the boss or cardinal muscular 

 fulcrum of other genera. 



From the margin of the crural base arise two slender processes, one on each side of, 

 and immediately adjoining, its centre (PI. VIII, figs. 3, 4y) : they curve upwards to 

 nearly the anterior end of the arch, just within touching it. These processes, which 

 I am disposed to regard as the homologues of the two curving plates (crura of the loop) 

 that strike ofi" from the hinge of the small valve in Hypothyris [psittacea), appear to 

 have been hollow, and to have passed through the crural base ; for occasionally casts 

 of their lower portion are seen, like two threads, starting from the centre of the space 

 occupied by the crural base, when the substance of the latter has been removed through 

 fossilization. Immediately below the structures just noticed, a large spatula-shaped 

 process is seen to originate and project with a slight upward curve nearly to the centre 

 of the shell (PI. VIII, figs. 3, 4, 5 e) : it becomes considerably dilated towards the free 



' Annals and Magazine of Natural History, vol. xiv, p. 313. 

 2 Idem, vol. xviii, pp. 89-91. 



