J. Starhie Gardner — On Cretaceous Aporrhaidce. 399 



It is found at Blackdown, where it is less common than D. calcarata. 

 An examination of a very large series of specimens fails to show any- 

 decided intermediate form between the two species. Mr. E. Tate, in 

 the Geol. and Nat. Hist. Kepertory, Sept. 1865, separated it as a 

 variety of Aporrhais calcarata, under the name of A. neglecta. 

 Dimorphosoma toxochila, 1 Gardner. Gault. PI. V. Figs. 10, 12. 



Shell elongated ; whorls 7 or 8, rounded, inflated ; keels obliterated, 

 except on apical and body- whorls, other whorls ribbed; ribs pro- 

 nounced, more or less oblique and flexuous, about a dozen on each 

 revolution ; sutures keeled ; apex rather obtuse, composed of three 

 smooth angulated whorls, with a strong keel rather anterior to their 

 centre. The last whorl is striated, and has two keels, the posterior 

 being the more prominent ; on the ventral side the region above the 

 posterior keel is ribbed. The inner lip is incrusted round the 

 aperture, the margin of the incrustation being sharply defined ; the 

 outer lip is prolonged into a very long, curved, narrow, and simple 

 wing, grooved ventrally, carinated above. The wing is straight for 

 a quarter of an inch, and is then curved rather suddenly upward, 

 exceeding the spire in length. Anterior canal long and nearly 

 straight ; aperture narrow. This shell is more elongated than the 

 Lower Gault species. It is found in the beds immediately above and 

 below the mottled bed in the Folkestone Gault, where it is rare. The 

 beds are numbered 5 and 7 by Mr. F. G. H. Price. It is more 

 elongate and slender than the Lower Gault species. 



Dimorphosoma dokatochila, 2 Gardner. Gault. 



Shell moderately elongated ; whorls 6, sometimes 7, convex, finely 

 and distinctly striated ; keels obliterated except on apical and body- 

 whorls ; the third whorl is both keeled and ribbed, the other whorls 

 are ornamented by numerous oblique and flexuous ribs ; sutures 

 raised, sometimes hidden ; apex formed of three broad and very 

 obtuse angulated whorls, which are smooth, with a strong median 

 keel. The body -whorl has two keels, the posterior being the more 

 prominent ; the posterior region is slightly ribbed ventrally ; the 

 whorl is strongly striated, especially that part anterior to the keels. 

 The wing is long, narrow, simple, forming an acute ridge above ; it 

 is curved gradually upward, and terminates in a sharp point. The 

 aperture is narrow, and is incrusted immediately round the colu- 

 mellar lip ; the outer lip is toothed ; the wing is applied to the last 

 whorl only ; the anterior canal is long and straight. 



The history of this species is given at page 129, it is confined to 

 about a single foot of the Gault of Folkestone (bed 2 in Mr. Price's 

 paper), and has not been met with elsewhere. 



Dimorphosoma opeatoohila, 3 Gardner. Grey Chalk. PL VII. 



Fig. 9. 

 Shell very elongated ; whorls rounded, probably nine ; striated ; 

 keels entirely obliterated, except on the body-whorl ; ribs ten or 

 eleven on each whorl, reaching to the sutures. Last whorl having 



1 r6t,ov, a bow. 2 Sopv, a spear. 3 07reas, an awl. 



