J. Siarkie Gardner — On Cretaceous Aporrhdidce. 397 



Found in the Cracker rocks at Atherfield. Described from two 

 specimens in the Jermyn Street Museum. 



Dimokphosoma ancylochila, 1 Gardner. Neocomian. PI. XII. Figs. 2, 2a. 



Shell elongated ; whorls 6 or 7, very angulated, their median keel 

 tuberculated, sutural keel plain, intervals smooth, without spiral 

 striee. The last whorl possesses two angular keels ; the posterior 

 considerably predominating, and the anterior being the sutural keel 

 of the spire ; the greater keel is continued into the wing. The wing 

 is narrow, simple, thick and angular like a roof-ridge ; for some dis- 

 tance it is at right angles to the axis of the spire, and then curves 

 gradually upwards, slightly expanding at the point of curvature. 



Found in the Cracker rocks at Atherfield. Described from a single 

 specimen in the Jermyn Street Museum. 



Dimokphosoma pletjrospira, 2 Gardner. Neocomian. PI. XII. 

 Figs. 3, 3a, 4. 



Shell elongated ; whorls 7 or 8, last two rounded, upper whorls 

 angulated, possessing three keels. On the upper whorls the first 

 keel is strong, salient, and tuberculated, with 9 or 10 tubercles on 

 each whorl ; the second keel is indistinct ; the third is well marked 

 and sutural ; on the penultimate whorl the two keels assume about 

 equal prominence, the upper one being still faintly tuberculated; 

 the last whorl has all three keels well developed, the median one 

 being least prominent. The wing appears to be strong, and projected 

 slightly downward. The shell is unusually destitute of spiral striae. 

 Under the microscope faint transverse structural lines are visible. 



This species is found in the Lower Greensand at Peasemarsh. 

 Mr. C. J. A. Meyer has several specimens in his collection, the most 

 perfect of which are selected for illustration. 



Dimokphosoma vectiana, Gardner. Aptien. PL XII. Figs. 5, 6, 7. 

 (Insula Vectis, Isle of "Wight.) 



Shell elongated ; whorls 6 or 7, angulated ; upper keel replaced by 

 rather produced, elongated tubercles, except on the last whorl ; 

 sutural keel smooth and distinct ; last whorl with two salient keels, 

 rather close together, the posterior being the more prominent ; spiral 

 striae none, except on the dorsal- side of the anterior canal ; the wing 

 is simple and curved upward, elongate, and narrow ; anterior canal 

 moderately long. 



Found at Shanklin, in the Folkestone beds of the Lower Green- 

 sand. Mr. Meyer has kindly shown me about a dozen specimens in 

 his collection, three of which are selected for figuring. Fig. 7 is 

 from a cast only, the shell having broken away ; the canal and 

 wing process are, however, well preserved. 



Dimorphosoma sp. ? Aptien. PI. XII. Fig. 8. 

 A cast of an Aptien species with expanded wing is represented at 

 Fig. 8. It is probably distinct from that described above, and is from 

 the same locality. 



1 ajKvAis, a hook. z irXevpa, a rib. 



