ANIMALS. 177 



from each umbone to the pallial line, at the same time curving slightly towards the 

 posterior end. (Vide PI. XV, fig. 22.) 



Leda Vinti, which is a rare species, .occurs in the lowest beds of Whitley and 

 Humbleton Quarries, and in both the compact and crystallized rocks near Byers's 

 Quarry. According to Geinitz, M. Mielecki has discovered it in the Zechstein-dolomite 

 of Katzenstein, in the Hartz. 



Family/ Solemyid^, Philippi. 



" The very singular SolenomycB ought to constitute a family of themselves, the gills 

 not being lamellate, but twice pectinate or pinnate : the mantle is closed, attached 

 to the whole of the shell, not reflexed at the ventral margin : siphons none, the 

 aperture for the anal excretions, and for the branchial water being undivided. 

 Epidermis shining, reaching beyond the margin, and elegantly slashed ; not of a 

 horny substance, for, when treated with caustic potash, it does not exhale ammonia, 

 but seems rather of a glutinous nature."^ (Philippi.) 



This very singular family has now existed during an immense lapse of time on our 

 planet. Professor Phillips, by his discovery of the so-called Solemya primcsva, was the 

 first to make known its having lived during the Carboniferous epoch. I have else- 

 where noticed my discovery of species belonging to the Devonian rocks of the Eifel, 

 and to the Magnesian-hmestone formation of Durham.^ I am not acquainted with any 

 secondary or tertiary forms ; but their having existed during the primary period, and 

 their being now wide-spread denizens of our seas, are, in my estimation, positive 

 proofs of the family having lived during the intermediate periods. The recent Solemya 

 and the palaeozoic Janeia are the only genera known belonging to the group. 



Genus Janeia, King. 



Diagnosis. — Oblong : inequilateral, the posterior side being the longest. Cartilage 

 internal; attached to a considerable portion of, and a little within, the dorsal margin 

 of the valves; dilated, and somewhat oval within the umbonal ca\'ity; narrow, and 

 elongated behind it.''^ 



Type, Solemya primaev a, Phillips. 



1 Enuraeratio MoUuscorum Sicilise, p. 15. 



2 London Geological Journal, vol. i, p. 10. 



2 For further remarks on this genus, see Appendix. 



