436 C. D. Sherhorn — Hipponyx from the White Chalk. 



EXPLANATION OF PLATE XIV. 



Fig. 1. — Ti/phlonisctisprinceps, S'p.Tioy. Head-shield, x 2.' Sholeshook Limestone : 



Sholeshook railway cutting, Haverfordwest. 

 ,, 2. — Ditto. Side view of same specimen, showing projection of anterior end of 



glabella, x 2. 

 ,, 3. — Ditto. Portion of surface of cheek, x 4. 

 ,, 4. — Zi/ffospira ITasweUi, sp. noY. Internal cast of shell, pedicle-A'alve. x 2 J. 



Llandovery Beds : The Frolic, Haverfordwest. 

 ,, 5. — Ditto. Another specimen, x 2|. 

 ,, 5ff. — Ditto. Brachial valve of same specimen, x 2^. 

 ,, 6. — Ditto. Internal cast of shell, brachial valve, x 2^. 

 ,, 7. — Ditto. Posterior view of internal cast of another specimen, x 2|. 

 ,, 8. — Ditto. Impression of exterior, umbonal region, showing delthjTium in 



pedicle-valve, x 2^. 

 ,, 9. — Ditto. Impression of surface of valve, sho^^ing ribbing and concentric 



stria tion. x 2|. 



II. — On tavo new Gasteropods {Hipponyx black^iobei and 



H. DIBLETl) EKOM THE WhITE ChaLK. 

 By C. Davies Sherborn, F.G.S., F.Z.S. 



SOME years ago Dr. H. P, Blackmore called my attention to some 

 fragmentary remains of shell on Echinoids whicli he had found 

 in the Salisbury district. These he regarded as belonging to Hipponyx. 

 The true relationship of these fragments could not, however, be con- 

 sidered certain until Mr. Dibley found the almost perfect example seen 

 in Fig. 1. Dr. Blackmore's finds are recorded in the list of fossils in 

 the " Cretaceous Kocks of England " (Mem. Geol. Survey), iii, p. 473, 

 as " Salisbury," but I have not discovered what form is there referred 

 to under the localities of " East Kent" and " Margate." 



Hipponyx hlachnorei, n.sp. 



Shell thin, bearing numerous close but coarse radiating ribs, which 

 are ornamented by swellings, becoming at the margin definite and like 

 rows of beads. Apex unknown. Base thin, fairly regular, perfectly 

 smooth, occupying three parts of the area. 



Type. — Blackmore Collection, on an JEchinocorys from the Actino- 

 camax quadratus Chalk, East Harnham, near Salisbury. Partly 

 overgrown by a Spondyhis. Fig. 2, x 2. Another specimen, Black- 

 more Collection, on a Micraster from the Micraster cor-angtiinum Chalk 

 from Quidhampton. This specimen is in much the same condition as 

 the last, but shows a little more margin of shell. As it does not 

 show any base, it may not be in its original position. 



Hipponyx dihleyi, n.sp. 



Shell thin, with numerous close, radiating, fine ribs ornamented by 

 irregular swellings, which persist to the margin of the test and do not 

 appear to become bead-like. A few concentric lines of growth. Apex 



' Marked in error on plate as magnified H times. 



