23 



Pleurotomaria occidens, Hall. 



Pkuroiomaria ocddens, Hall. Twentieth Eeg. Rep., p. 364, pi. 15. figs. 11 and 12. 



Elora, T. C. Weston, 1857 : one specimen, identified with the above 

 species by B. Billings. 



Plexirotomaria Valeria, Billings, 

 Plate 4, figs. 1 and la. 



Pleurotomaria Valeria, Billings. 1865. Pal. Foss., Vol. I., p. 169. 



The type of this species, which is only a cast and which was not 

 figured, has the whole of the spire buried in the matrix so that the 

 basal suj.-face and pai*t of the body-whorl only are exposed. Two or 

 three fine specimens with the test preserved have recently been 

 collected at Durham by Mr. J. Townsend, the best of which is repre- 

 sented on plate 4, fig. la. These give a good idea of the characters 

 and surface markings of the upper portion of the shell. On the spire 

 the test appears to be nearly or quite smooth, but on the upper half of 

 the last volution the sculpture consists of crowded and rather flexuous 

 transverse striations. The species may be readily known by its 

 depressed-tui'binate form, its sub-angular whorls, its prominently and 

 distinctly keeled periphery and its wide open umbilicus. 



Pleurotomaria cyclostoma. (N. Sp.) 

 Plate 3, figs. 12 and 12a. 



Shell conical, a little broader than high: 'whorls about five: spire 

 moderately elevated, occupying about one half the entire height, its 

 whorls flattened obliquely: last whorl but one bearing in its centi-e a 

 narrow spiral band which is bordered on both sides by a thread-like 

 and minute raised ridge: band quite obsolete in the first and second 

 volutions, and nearly so in the third : suture indistinct. Body-whorl 

 with the periphery angulated and carinated, the keel being narrow, 

 acute, simple and prominent : band placed half way between the keel 

 and the suture : base nearly flat, impei'foi-ate : aperture circular. 



Body-whorl (and perhaps the lower portion of the spire) marked by 

 crowded transverse striae or lines of growth : on the upper part of the 

 body-whorl these striae appear to be insinuated convexly backwards 

 towards and to the band, while on the lower face of the same whorl 

 they radiate concavely backwards : the outer margin of the basal 

 portion of the body- whorl also is marked by two or three faint spiral 



