250 G. Sharman and E. T. Newton— 



Gasteropoda.. 



Troclms pulcherrimus, Phil. — Several specimens, about one-third of 

 an inch in length, referable to this species, have been recognized ; 

 Phillips' figure of a specimen from the Speeton Clay is scarcely 

 sufficient to allow of identification; but examples in the Museum 

 of Practical Geology and in Mr. Lamplugh's collection seem to 

 be identical with the Moreseat specimens. There is some slight 

 variation to be traced among the specimens from each locality ; but 

 all seem to be characterized by two keels, more or less crenulated, 

 one at the lower part and another at the upper part of each whorl, 

 between which there is a broad, concave area, marked by numerous 

 fine, oblique threads, running in the direction of the lines of growth, 

 and crossed by a few longitudinal threads. The flattened base is 

 similarly marked by two sets of lines, which, being much coarser, 

 give a more cancellated appearance to this part of the shell. There 

 is no umbilicus, and the mouth is nearly round. 



Trochus, sp. — Another form, about half an inch in length, which 

 we refer to this genus, is likewise represented in the Speeton Clay ; 

 its sides are flat, and the sutures are not depressed, so that it forms 

 an almost complete cone with flattened sides. At the top and bottom 

 of each whorl there is a slightly crenulated ridge, and between these 

 there appear to have been fine, oblique lines of growth. 



Acteson, sp. — Two or three specimens referable to this genus 

 have been noticed : the body-whorl is inflated and marked by a 

 few (four or five) impressed lines ; the spire is little more than 

 half the height of the body-whorl. 



Cerithium acaleatum, Forbes MS., var. — There is one mould of 

 a Cerithium very well preserved, which agrees so closely with the 

 specimens from Speeton, to which Prof. Forbes attached the above 

 name, that we feel assured it is the same species, or, at most, a 

 variety of it; and we gladly adopt the name, although no description 

 of the species has yet been published. The Moreseat specimen is 

 -rg-ths of an inch long and ith of an inch wide at the largest part ; 

 and one may count 13 or 14 whorls. Each whorl has a strongly- 

 marked nodular ridge near the top, and another, slightly smaller, 

 at the base ; between these are two, sometimes pei'haps three, 

 thread-like lines, and there are indications of a fine line at the top 

 and another at the base between the suture and the larger ridges. 

 The base of the last whorl is rounded and marked by four to six 

 longitudinal lines. The whorls are crossed obliquely by strong 

 ribs, eight of which may be seen at one time on the lower whorls. 

 The ribs are large above and rapidly attenuate below, and where 

 they cross the longitudinal lines produce nodular markings. 



Compared with the Speeton Clay C. aculeatum, it will be noticed 

 that in the latter the ridges and ribs are more sharply cut, and the 

 thread-like lines at the top and base of each whorl are more 

 definite ; and, further, each whorl has three longitudinal lines 

 between the two larger ones; also, about nine ribs may be counted 

 on one side of each whorl. 





