JORDAN : NEW BKITISn MOLLUSCA. 265 



B. agile "is not* always so faintly striated as described by Sars." 

 It differs from I). striolaUim in its more slender form and stronger 

 sculpture; from D. candidum in its much more slender form, and 

 in not possessing the fine transverse intercostal sculpture of that 

 species ; whilst from D. dentalis it is distinguished by its more slender 

 form, more numerous ribs (about twice as many), which are thin 

 and not well rounded as in D. dentalis, and by not having longitudinal 

 microscopical strice between the ribs. 



The learned author of "British Conchology," in vol. iii, p. 197, 

 says of JD. dentalis, "It has nine longitudinal ribs, besides fre- 

 quently a stria between each rib, but no fine impressed lines as in 

 I). Tarentinum^^ ; but in the specimens of D. dentalis which I 

 have examined longitudinal striae are visible ; even in specimens 

 which appeared to be destitute of them, I have with a strong lens 

 detected them in some places when holding the shell at a certain 

 angle to the light, and in many specimens these strife, by their 

 intersection with the lines of growth, impart a microscopical bead- 

 work appearance to the intercostal spaces. 



IsIy. E. a. Smith informs me that there are two specimens of this 

 new species in the British Museum (Natural History) from off the 

 west coast of Ireland in 1000 fms., and that he regards the species as 

 being quite recognizable. 



PuNCTUKELLA Chasteet, n.sp. PL XVI, Fig. 2. 



Shell resembling P. Noachina, but smaller and more depressed. 

 Sculpture much finer ; twice as many ribs, which are uniform in size 

 and not alternately large and small. These ribs extend from the 

 margin to the crown, whereas in P. Noachina the intermediate ribs 

 almost invariably extend only about half way up. Near the apex 

 there are concentric raised threads, which by their intersection with 

 the ribs produce a well-marked cancellation. Long. 5, diam. max. 4, 

 min. 3 mm. (L. 0'190, B. 0-125). 



A single specimen from the ""Warm area." I have pleasure in 

 naming this species after my friend Dr. G. W. Chaster, of Southport. 



Tkochus (Margarita) tetragonostoma, n.sp. PL XVI, Fig. 3. 



Sliell forming an obtuse and slightly oblique cone, about as broad 

 as high, with a strongly keeled periphery, solid, opaque, and 

 colourless. Sculpture, six or seven spiral grooves on the base of the 

 shell, which is somewhat flattened, and one spiral groove above and 

 close to the periphery. The body and penultimate whorls have 

 numerous longitudinal ribs, which on the body-whorl are almost 

 obliterated, except on the upper part. The upper ends of these 

 ribs form a series of slight nodules. The three uppermost whorls 

 are destitute of ribs. Spire moderately raised. Whorls five : the 

 three uj^per ones rounded, the penultimate less rounded, and the body- 

 whorl flat. Suture very narrow and deep. Mouth presenting an 

 irregidar four-sided figure. Outer lip, above forming almost a right 

 angle with the base of the body-whorl. Inner lip folded over the 



