GASTEROPODA. 29 



DENTALIUM PARKINSONI, Quenst. Der Jura, p. 484, t. 65, figs. 5, 6. 

 ENTALOIDES, Oppel. Die Juraformation, 1856-8, p. 390. 

 ANNULATUM, Bean, Leckenby. Journ. Geol. Soc., 1858, vol. iv. 



Testa crassa, tereti, subarcuata, scepius nitida, slriis tenuissimis densissimis paululim 

 obliquis ornata. (Deslongchamps.) 



Shell thick, tubular, round, smooth, shining, slightly curved ; encircled with striations, 

 which are somewhat oblique and strongly impressed towards the posterior or smaller 

 extremity, anteriorly they are more faintly and densely arranged and ultimately disappear, 

 the surface having some irregular annular folds of growth. Length of an imperfect Corn- 

 brash specimen 24 lines, the larger diameter 2~ lines. The Calcareous Grit examples have 

 larger dimensions, they are of more advanced growth, and have the greater portion of their 

 cylinder devoid of striations. 



The Cornbrash imperfect specimens are less slender and more straight than the figures 

 of I). Parkinsoni given by Professor Quenstedt, and more nearly accord with those of 

 D. entaloidcs, Deslongchamps ; but the specimens figured by Quenstedt differ also from 

 each other in their attenuation and curvature. Dentalium cinctum, Goldfuss, has encircling 

 striations, without obliquity ; D. undulatum of the same author has the figure some- 

 what compressed ; D. tenue, Goldf., is more slender and more nearly cylindrical. 



Geological Position and Locality. Denlalium entaloides appears to have a considerable 

 geological range; the Cornbrash of Scarborough has produced a few specimens; Mr. 

 Leckenby has also obtained it in the Kelloway Rock and the Calcareous grit of the same 

 locality. D. entaloides was obtained by M. Deslongchamps in the Inferior Oolite of 

 Moutiers and Bayeaux ; by Dr. Oppel in the beds with Ammonites Parkinsoni at Mont 

 d'Or, near Lyons; in Svvabia it occurs at the upper boundary of the Lower Oolite (Braun 

 Jura e. Quenst.) at Ehningen and Balingen. 



TROCHUS STRIGOSTJS, Lye. Tab. XLV, fig. 12. 



Testa alta, conica, transverse costellata, costellis granulosis asqualibus ; anfractibus (5) 

 subplanis, quadricostatis et vitta striata antcriora ; ultimo anfractu obtuse carinato ; basi 

 concava ; columella obliqua ; apertura sub-triangulari. 



Shell elevated, conical, transversely costellated ; costellae, four to a volution, granulated 

 and equal ; the anterior border of each volution has also a depressed, striated band ; the 

 volutions, about five in number, are flattened, and the last volution is rounded ; the base 

 has a few striations ; the columella is oblique, and the aperture somewhat triangular. 



The ornamentation is strongly marked and regular ; the height and breadth are nearly 

 equal ; the sole specimen is rather imperfect at the apex. 



Geological Position and Locality. The Cornbrash of Gristhorp Bay, near Scar- 

 borough, in the collection of Mr. Leckenby. 



