396 J. Starkie Gardner — On Cretaceous Aporrhdiclce. 



the mantle, and possibly they were formed of the material absorbed 

 from the wing. There is a case recorded by Mr. J. Gwyn Jeffreys 

 which is of interest as throwing a side light on this subject. Speak- 

 ing of Pleurotoma, he writes : "A specimen in my cabinet, from the 

 body-whorl of which a large piece had been taken away at one time, 

 exhibits a peculiar sort of repair ; the renewed portion has no trace 

 of longitudinal ribs, although the spiral sculpture is replaced." 1 



If the growth was as I suggest, it follows that the ribs are not 

 homologous with the varical ribs of Scalaria. Mr. Eeeve and others 

 have long since drawn attention to the solvent properties of the juices 

 of Cyprwa, Conus, etc. ; whilst Murex and other varicose Gasteropoda 

 have the power of removing portions of the varices or spines of the 

 last formed whorl, which would obstruct the growth of the over- 

 lapping succeeding whorl. Many Cerithia, which in their younger 

 stages have dilated lips or recurved canals, surely must possess this 

 power, and this remark also applies to Persona, Cassis, Typhis, 

 Bicinula, etc. A different opinion is, however, held by Mr. Gwyn 

 Jeffreys, who, for no reason, as far as I can find, that he has given, 

 objects to this view. 2 In the present case we must suppose the mantle 

 to have been spread as in Sycotypus (Pyrula) ficus, but still conforming 

 to the shape of the shell, which enabled it to absorb from the dorsal 

 side. It seems doubtful whether the form of any of the recent 

 winged families would enable them to produce their shells in this 

 manner. 



Genus Dimobphosoma, 3 Gardner. 



Shell fusiform, with dilated wing, spire elongated : always pos- 

 sessing two, rarely three keels, which are generally obscured, except 

 on the apex and last whorls, by transverse ribbing ; whorls numerous, 

 usually finely striated, sometimes smooth, either keeled or ribbed 

 transversely ; apex more or less obtuse ; aperture narrow ; with a 

 long or short canal in front ; outer lip expanded into a simple grooved 

 digitation. The wing attached to the last two whorls only. 



Dimoephosoma kinclispiba, 4 Gardner. Neocomian. PI. XII. Figs. 1, la. 



Shell elongated ; apex obtuse; whorls 7 or 8, inflated and rounded, 

 ornamented by numerous longitudinal oblique, flexuous ribs, extend- 

 ing to the sutures. The ribs vary in number and prominence, there 

 being about twenty and fourteen respectively on the penultimate 

 whorls of the two known specimens ; they are crossed by numerous 

 distinct, irregular raised spiral stria?, which are seen with an inch 

 power to be angulated. The upper side of the last whorl is destitute 

 of ribs, but has a very salient median keel, and a second subordinate 

 keel in front ; one of the spiral lines between the keels is more dis- 

 tinct than the rest. The canal appears to have been long ; the 

 margin of the outer lip in front of the wing is angulated ; the wing 

 is simple, strong and ridge-like, projected slightly downwards. 



1 J. G. Jeffreys, vol. iv. p. 397. 2 Ibid. pp. 306, 403. 



3 Two-shaped body. 4 Kiyn\is, a lattice. 



