belonging to the Class Palliobranchiata. 91 



seen in the ventral valve of any other Palliobranchiate genus ? 

 As far as my own observations extend, I have not yet become 

 acquainted with a single instance of the kind. 



M. VerneuiPs principal reason for maintaining the genus 

 Pentamerus is founded on an alleged wide dissimilarity between 

 its internal apparatus and that of all other cognate genera : it 

 has been shown however that the amount of dissimilarity is not 

 so great : nevertheless, very few will be disposed to question the 

 validity of this genus, inasmuch as it possesses a combination of 

 characters peculiar to itself. This is no more than may be 

 claimed for Camerophoria, which, until it is known that a project- 

 ing process for the support of the valvular muscles exists in the 

 lower valve of other Palliobranchs, may be considered a more 

 isolated genus than Pentamerus. 



Reverting to the remaining characters belonging to Camero- 

 phoria, the platform appears to be the same as the crural base 

 (in this case a flat one) of Terebratula, and may therefore have 

 supported the inferior pedicle muscles. The filiform processes 

 I am disposed to look upon as supports for the labial appendages 

 and the visceral parts of the mollusk. 



It may be asked, is not the valvular muscular process in the 

 ventral valve of Camerophoria, the plates of Pentamerus united ? 

 Considering the definition previously given of a socket-plate, I 

 am certainly disposed to think that it is not : the latter being 

 prolongations of the socket-walls, compels us to consider them as 

 true socket-plates; but as regards the former, its total want of 

 connexion with the sockets, and its striking off from below the 

 centre of the free margin of the platform, strongly support the 

 view that it is the mesial plate to be seen in the lower valve of 

 many shells (Atrypa concentrica, Terebratula rostrata, Hypothy- 

 ris pugnus, Orthis Michelini, Strigocephalus, &c.) bilaterally ex- 

 panded on its superior margin. 



Camerophoria appears to have an extensive geographical range. 

 M. Verneuil has collected two species in Russia, C. Schlotheimi 

 and C. superstes, the former in the carboniferous limestone and 

 the latter in the lowest beds of the Permian system. I have 

 specimens of an allied species from the mountain limestone of 

 Weardale. The genus abounds in the magnesian limestone near 

 Sunderland, and in the Zechstein of the Thuringer-Wald : in 

 the former locality three, if not more species are found. The 

 strong external resemblance which Camerophoria bears to certain 

 carboniferous and Devonian shells, leads me to think that it will 

 hereafter be found to comprise a number of species*. 



* As M. Verneuil's objection to the genus Camerophoria appears t.: be 

 founded only on a knowledge of the structure of the dorsal valve, it will be 

 unnecessary to say more than that, if the species belonging to it differed from 



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