398 ON THE MOLLUSCA OF THE 'TRITON ' EXPEDITION. [JuilC 1 9, 



^ 10. Pleurotoma exigua', Jeffreys. (Plate XLIV. fig. 10.) 



Shell oblong, solid for its size, semitransparent, and rather 

 glossy : sndphire, numerous regular and close-set spiral strise, which 

 are crossed by less conspicuous longitudinal rib-like striae ; the 

 direction of these last follows the line of growth ; the intercrossing of 

 the two sets of striae produces a delicate reticulation ; the uppermost 

 whorl is quite smooth and shining : colour milk-white : spire some- 

 what turreted, gradually tapering to a blunt point, and apparently 

 truncated : whorls ^\, concave ; the last occupies two thirds of the 

 shell ; the uppermost whorls form a bulb, and the half-whorl at 

 the point is twisted inwards : suf.vre deep : month or aperture oblong 

 and narrowish, forming above a small ledge; length exceeding half 

 the shell : canal very short and wide, nearly straight, ending in an 

 obliquely rounded notch : outer lip obtusely angulated at the top, 

 and elsewhere gently curved ; edge thin and sharp : labial slit or 

 fissural groove short and shallow -.inner lip broad and glazed •.pillar 

 flexuous, sloping inwards to a cuttins'-edge : operculum not observable. 

 L. 0-2, B. 0-J5. 



A single specimen from Station 13, 570 fathoms. 

 This species is allied to P. {Bela) tenuicostata of M. Sars, but is 

 narrower ; the longitudinal ribs or striae are straight as regards the 

 line of growth (instead of being flexuous as in that species) ; the 

 spire is abrupt or apparently truncated at the top ; and the fissural 

 groove is much shallower. 



11. Cryptaxis crebripunctatus ^ Jeffreys, (Plate XLIV. 

 figs. 11, 11a, 116, lie.) 



Shell oval, thin, semitransparent, and glossy ; sculpture, very 

 numerous and regular fine spiral or revolving striae, which are 

 closely punctured ; they are stronger at the base than at the crown : 

 colour white : spire deeply sunken, and for the most part concealed 

 in a small cavity in the centre of the crown ; but the bulb-shaped 

 apex is visible at the bottom of the cavity : mouth semioblong, 

 contracted above and expanding below : outer lip slightly raised 

 above the crown and channelled, curved in the middle and at the 

 base : inner lip inconspicuous : pillar straight on the upper half 

 and incurved below. L. 02, B. 0). 



Three specimens from Station 13, 570 fathoms. 



In the 'Annals and Magazine of Natural History ' for June 1883 

 I indicated the probability that a species which was there described 

 and figured as Cylichna parvula might be the type of a distinct 

 genus, intermediate between Cylichna and Utriculus, because the spire 

 was partly concealed; and I suggested the name Cryptaxis. I am 

 now encouraged by the discovery of the present species to adopt the 

 above generic name. I would not refer these species to the genus 

 Bullinu of Ferussac, as defined by Messrs. Adams in their ' Genera 

 of Recent Mollusca,' who say " spire rather elevated ; .... coloured 

 markings ; outer lip grooved internally, and with the mar- 

 gin crenulated." None of these characters are applicable to either 

 ' Little. 2 Closely punctured. 



