42 MOLLUSCA FROM THE CRAG. 



the name of Figs as the type of his genus Pyrula. Mr. G. B. Sowerby, in his Genera 

 of Recent and Fossil Shells, had also previously excluded all others from this genus, for 

 which he retained the name of P}Tula ; and although the dissimilar shells still united 

 with these must hereafter be separated, the name of Pyrula ought to be retained for this 

 section. The recent species of this genus, or section, are found only within the tropics. 



1. Pyrula reticulata. Lam. Tab. II, fig. 12. 



Bulla ficus, var. 1. Broc. Conch, foss. Subap. p. 2/9, 1814. 



Pyrula reticulata. Byjard. Mem. de la Soc. Geol. de France, Ency. Meth. pi. 432, fig. 2. 



— Lam. An. sans. Vert. 2d edit. t. ix, p. 510. 



— S. Wood. Catalogue, Au. and Mag. Nat. Hist. 1842, p. 543, pi. 5, fig. 17. 



— G. Sowerby. Genera of Shells, fig. 1 . 



— Phil. En. Moll. Sic. vol. ii, p. 180, 1844. 



P. Testa jicoided, jji/riformi, venfricosd, tenui, cancellatd ; spird hrevissimd, convexd, 

 retusd ; anfradihm circa quatuor infatis ; aperturd amjdd, ovatd ; canali angustatd ; lahro 

 acido. 



Shell thin, ventricose, pear or fig-shaped ; spire short and convex ; volutions about 

 four, cancellated, transverse striae the more elevated ; aperture large, subovate ; with 

 an elongated caudal termination ; outer lip sharp. 



Axis, 3 inches. 



Locality. Cor. Crag, Ramsholt. Recent, Indian Ocean. 



My cabinet contains only two specimens of this shell, which appear to differ in 

 some slight degree from the Oriental species. The upper part of the outer lip is more 

 elevated, the whole shell is not quite so slender, and the transverse ridges are rather 

 broader and flatter. The specimen figured does not represent the canal so elongated 

 as it is in the recent specimens, but a portion of it is broken away; the lines of growth 

 indicate a similar length. 



If this be Pyrula reticulata of Lamarck, which I presume it is, its retirement or 

 migration to the southward and eastward might have been tln'ough the seas that 

 deposited the Touraine beds, whence, in all probability, it originally came, and 

 had an extension of existence through the more modern (?) deposits of Calabria, 

 in which it is found fossil, as quoted by Philippi. Conceiving a communication 

 to have then existed between the Mediterranean and the Arabian Gulf, a further 

 extension to its present habitat might have taken place through the channel now so 

 eff'ectually closed by the Isthmus of Suez. 



The presence of this species in a latitude so high as that of England has been 

 accounted for upon the supposition that the temperature of the sea by which the 

 Coralline Crag was deposited was more favorable to its existence than the seas of the 

 same latitude are at the present day ; but a very elevated temperature does not appear 

 to have been essential to its existence, if we may judge from its associates, Tricotropis 

 borealis, Nuctda pyyinaa, &c., which are now found only on our own northern coasts, 

 and in the Arctic Seas. The supposition that those northern forms at that time 



