MOLLUSCA FROM THREE HUNDRED FATHOMS — HEDLEY. 221 



angled at its centre by a tuberculate keel. In the series before 

 us the proportion of length to breadth varies considerably. 

 Whorls eight, including a protoeonch of a whorl and a half. 

 Colour pale cream with an evanescent purple tinge in the aperture. 

 Sculpture : the suture is slightly puckered by small radiating 

 folds which run out before reaching half way to the keel. Along 

 the keel are prominent wide spaced tubercles, numbering on the 

 penultimate about seventeen, each truncated in front and sloping 

 at the back to the base of its j^i'edecessor. Behind the aperture 

 these sometimes degenerate into crowded imbricate scales. 

 Below the keel the radial sculpture is resumed at indistinct for- 

 wardly curved riblets. Fine raised spiral threads extend fi'om 

 the tip of the canal to the protoeonch. In the hollow supra- 

 carinal shelf they are small and close together ; below the keel, 

 amounting on tlie last whorl to about forty, they are wider 

 spaced, often alternating in size and tend to be knotted by the 

 radials. Protoeonch smooth and very gh^ssy, dome shaped, a 

 whorl and a half, ending with a sinus. Aperture narrow, perpen- 

 dicular. Outer lip very deeply insinuate at the keel, then 

 sweeping forward in a full curve. Columella broad, heavily 

 calloused, excavate above, swollen and twistefl below. Length 

 1 7 mm. ; breadth 1 1 mm. 



Several specimens from two hundred and fifty fathoms. 



The lines of specific distinction appear to be drawn narrowly in 

 this genus and to depend chiefly upon sculjiture. The novelty 

 appears intimately related to Plenrotoma (GenofAa) engoiiia, 

 Watson,'^ differing by the sharper keel, more elevated tubercles 

 and generally coarser sculpture. 



It was evidant from literature that in size, shape and substance 

 our species made a near approach to certain Tertiary forms named 

 by Prof. R Tate. We therefore sought the opinion of Mr. J. Den- 

 nant on their inter-relationship, who very kindly replied, 14th 

 March, 1906, as follows :— 



" The Bathytoma submitted is allied to B. pritchardi^ Tate," 

 from the Gippsland Miocene, and to B.fontinnUi<, Tate,' a common 

 shell in the Oligocene beds at Spring Creek. From the first it is 



^ Watson — Jouni. Linn. Soc, xv., 1881, p. 40.5; Id. — Cliall. Rep., Zuol., 

 XV., 1886, p. 300, pi. XX., f. 7. 



« Tate— Journ. Roy. Soc. N. S.Wales, xxvii., 1893 (1894), p. 175, pi. x., f. 4. 



"^ Tate — hoc. cif., \\. 175, \A. x., f. 4. 



