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 multiplicata, the 
large valve possesses a fissure (Pl. VII, fig. 13 @), 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 
(galeatus). The dental plates pass from the fissure, one on each side of it, to nearly a 
third of the length of the shell (Pl. VIII, figs. 3, 4a): 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 (Pl. VIII, 
figs. 3, 4 6). 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 (Pl. VIII, figs. 3, 5c) attached on one side to the hinge, and 
free on the other: its centre is occupied with a small protuberance marked with lines 
or strize (Pl. VIII, figs. 3,4, 5d). This plate is considered to be the equivalent of 
the crural base, and the protuberance, the counterpart of the Goss or cardinal muscular 
Jwerum of other genera. 
From the margin of the crural base arise two slender processes, one on each side of, 
and immediately adjoining, its centre (Pl. VIII, figs. 3, 4g): they curve upwards to 
nearly the anterior end of the arch, just withm touching it. These processes, which 
I am disposed to regard as the homologues of the two curving plates (crura of the loop) 
that strike off from the hinge of the small valve in Hypothyris (psitiacea), 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 (Pl. VIII, figs. 3, 4, 5): it becomes considerably dilated towards the free 
1 Annals and Magazine of Natural History, vol. xiv, p. 313. 
2 Idem, vol. xviii, pp. 89-91. 
