APPENDIX. 247 



Mediterranea. In none of the descriptions which I had read of Solemya is there any allusion made to its 

 having a double or divided cartilage, or to that division, which is situated within the umbonal cavity ; only 

 the large triangular portion, placed on the short side of the shell, is noticed. As my casts of Solemya 

 primceva exhibit the impressions of the umbonal division of the cartilage, and not those of the triangular 

 portion (this last circumstance is explained by the peculiar way in which the cartilage is attached to its 

 fulcra), I was induced to infer, that this fossil differed from the recent species noticed, in having the car- 

 tilage undivided, and situated within the umbonal cavity. Further : from the prevailing misapplication of the 

 terms anterior and posterior to the two extremities of Solemya, in consequence of its being generally under- 

 stood that the cartilage, in the recent species, is situated on the posterior end, that is, on the short side, — and 

 from the impressions of this structure, in the fossil species, being underneath the umbones, and consequently 

 on the opposite or long side, — I was also led to infer, that the latter differed from the former, in having the 

 cartilage placed within the umbonal cavity, and not behind it. That those conchologists, however, are in 

 error, whose description of Solemya states, or implies, that the cartilage is situated on the posterior side of 

 the valves, will be readily perceived by a reference to the figures of the animal of Solemya Mediterranea in 

 Philippi's 'Enumeratio MoUuscorum Sicilise,' and in plate 115 of the Atlas of 'Les Mollusques,' accom- 

 panying the 'Eeunion' edition of Cuvier's 'Regne Animal,' — which figures show the remarkable and 

 singular peculiarity of one of the divisions of the cartilage placed in front of the umbones, over the oral 

 apparatus, where the lunette is usually situated in other bivalves. 



I shall, in the next place, introduce a diagnosis of Solemya, which I am desirous should be substituted for 

 the section on Janeia in page 177. 



Genus Solemya, Lamarck. 



Diagnosis. — Transversely elongated : equivalved : inequilateral, the posterior side being the longest : 

 obtuse at the extremities. Epidermis shining; reaching beyond the margins of the valves. Umbones 

 scarcely prominent. Cartilage internal ; divided ; one portion (the largest) situated in front of the 

 umbones on two oblique lameUiform callosities or fulcra, having their free margin slightly separated from 

 the inner surface of the valves, — the separation containing the cartilage ; the other and smallest portion 

 slightly spreading over the inner surface of the valves within the umbonal cavities. Pallial line entire, and 

 marginal. 



Gasteropoda (Carnivorous) . 

 I have elsewhere noticed (Vide London Geological Journal, vol. i, p. 11 ; and description of plate xv, 

 lines 7 and 8) the drilled holes observable on some of the fossils described in the present Monograph, 

 and which indicate the existence of Carnivorous Gasteropods during the Permian period. The following are 

 the shells in which I have observed these perforations, — Bysso-arca tumida, Mytilus squamosus, Epithtjris 

 sufflata, and Trigonotreta multiplicata. 



Calyptrcea antiqua, Howse. 



A doubtful fossil, with this name, is described as foUows in the 'Transactions of the Tyneside NaturaUsts' 

 Field Club,' vol. i, p. 242. 



" Shell small, pateUiform ; strongly ribbed longitudinally ; margin crenulated ; two deep furrows 

 internally, from the apex to the margin, corresponding with two strong ribs on the outer surface. 



" In Magnesian limestone ; rare. Tunstall Hill. 



"Only one small specimen of the shell has occurred. The characters noted above are very conspicuous, 

 and its strong resemblance to many Calyptrsea has induced us to place it in that genus." 



