92 1NVERTEBRATA. 



GASTEROPODA. 



(See ante, p. 19.) 



APORRHAIS (TESSAROLAX) GARDNERI. 

 (Plate in., fig. 2, 2 a.) 



Aporrhais (Tessarolax} Qardneri, sp. nov. 



Tessarolax, n. sp. J. S. Gardner, ' Cretaceous Gasteropoda,' Geol. 



Mag., 1880, Vol. vn., pi. iii., f. 2, p. 50. 



"This fragment possesses all the characters of a Tessarolax, 

 and is similar in shape to T. retusa, the small extent of the region 

 in front of the keels giving the shell a truncated instead of a pear 

 shape. The species is evidently finely striated, and the keels 

 appear to have been slightly tuberculated as in T. Fittoni. It 

 was a larger shell than either of the Gault or Neocomian forms ; 

 but less than the grey chalk T. oligochila. It is scarcely suffi- 

 ciently perfect to furnish specific characters." 



Locality. Upware (Coll. Mr J. F. Walker, unique). 



APORRHAIS (TRIDACTYLUS) WALKERI, Gardner. 

 (Plate IIL, fig. 3.) 



Tridactylus Walkeri. J. S. Gardner, Geol. Mag., Vol. vii., pi. 

 iii., f. 4, p. 50. 



" Shell elongate and pupseform ; whorls irregular, inflated, not 

 forming a regular cone ; possessing a strong central keel, a second 

 and less prominent keel in front, and two partly concealed sutural 

 keels. The body-whorl has two nearly equal keels (slightly 

 diverging towards the outer lip, the front one being the less promi- 

 nent), and three smaller keels which are arranged above, below, 

 and between the primary keels. All the keels seem to have been 

 tuberculated, and the spire was probably ribbed, as in T. Grif- 

 fithsti, which it generally resembles. Length of fragment, 22 mm. ; 

 diameter of body-whorl, 12 mm. \ 



