PLEUROTOMARIA BUCHIANA. 93 



agree in most respects, except that the latter is drawn with an umbilicus and is not 

 so angular at the circumference. Hebert and Deslongchamps figure both species, 

 and our specimen agrees with their figure of T, helius, but not with D'Orbigny's in 

 having only a needle-point umbilicus. They suggest, however, that there is only 

 one species, in which case we must use the first-mentioned name according to the 

 rules of priority, and that of the commonest according to the rules of utility ; for 

 both reasons the name must be Ataphrus halesus. 



Genus PLEUROTOMARIA, Defrance. 



There is only one record of Pleurotomaria : 



*P. granulata (6, 25, 28, 34, 58). 



The specimens here referred to were first recorded under this name by Bean, 

 and certainly they resemble one of the figures given by Sowerby. This, being' 

 repeated by Leckenby and Wright, was finally figured by Lycett, and since then 

 the name has been adopted for the Cornbrash fossil by other writers. Hudleston, 

 however, points out that it is quite a different species, but has not provided a 

 new name. There is no difficulty in finding the proper one. 



Pleurotomaria buchiana, D'Orbigny. Plate VIII, figs. 23, 24. 



1845. Pleurotomaria buchiana, D'Orbigny in Murehisou, Verneuil, and Keyserling, Geol. Eussia, 



vol. ii, p. 451, pi. xxxviii, figs. 1, 2. 

 1863. granulata, Lycett, Suppl. Great Ool. Mollusca (Pal. Soc), p. 24, pi. xxxi, fig. 8. 



1885. — Hudleston, G-eol. Mag [3], vol. ii, pi. iii, fig. 8. 



Type. — " Shell broader than high, thick ; spire formed with a regular angle, 

 composed of slightly convex whorls, angular above, ornamented with unequal 

 longitudinal strise, which are crossed by lines of growth, more easily seen in the 

 young. The last whorl is keeled on the upper side. Umbilicus closed, or nearly 

 so. Mouth triangular, depressed. Sinus very short and placed on the lower third 

 of the whorl, forming the keel. Spiral angle 85°, length 31 mm., height of last 

 whorl 41 mm." From the Middle Oxfordian of Russia. 



Description. — Having an example from the typical locality in hand, it is easy to 

 verify on it the description given by Hudleston (I.e.) of our own species. " Shell 

 short, step-like, with the rudiments of an umbilicus. Body whorl about half the 

 height of the spire, whorls about six in number, sloping in the posterior two-thirds, 

 nearly vertical in the anterior third. The ornaments consist of numerous fine 

 spirals, which present" very distinct "nodes at the points of contact with the very 



