34 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 22, 



OstrjEA arietis, Quenstedt, 1856. 



Ostrcea arietis, Quenst. der Jura, t. 10. f. 10. 



On two slabs of sandstone from Lussay, obtained from the Lower 

 Lias beneath the coral-bed, there are a number of small plaited 

 Oysters which resemble Quenstedt' s Ostrcea arietis ; they are not 

 identical with the figure in his " Jura," but they resemble it more 

 closely than any other described species I am acquainted with. 



Pentacrinus robusttjs, Wright. 



Pentacrinus Goldfussii, Wright, 1854, Annals and Mag. of Nat. 

 Hist. 2nd series, vol. xiii. p. 380, pi. 13. f. 3. 



This Pentacrinite is a very characteristic Crinoid of the Middle 

 Lias of Gloucestershire, where it has been collected with Ammonites 

 capricornus, Schlotheim (A. maculatus, Young & Bird), at Chipping 

 Campden, and at Hewletts near Cheltenham, in the same zone. 



The plates of the column are thin ; each fourth or fifth plate is 

 broader, and projects beyond the plate below and above it. 



The pelvis and primary and secondary arms are very robust, 

 hence the specific name ; I originally figured and described this 

 species as Pentacrinus Goldfussii, Wr., before I was aware that 

 Professor M'Coy had previously given the same name to another 

 species ; it will therefore be figured in my monograph on the Oolitic 

 Echinodermata as Pentacrinus robustus. 



Mr. Geikie collected five fragments of the column of this species 

 from the micaceous shales at Pabba. 



Pentacrinus gracilis, Charlesworth, 1847. 



Pentacrinus gracilis, Charlesworth, London Geol. Journal, t. 9. 



The specimen is not in good preservation ; it consists of a portion 

 of the calyx, with its primary and secondary arms ; the bifurcation 

 of the primaries, almost as soon as they branch from the calyx, and 

 the long, simple, cylindrical, secondary arms, without pinnules, suf- 

 ficiently distinguish this species from its congeners. It is contained 

 in a highly micaceous fossiliferous slab of the Pabba-shales ; nearly 

 the same horizon in the Lias as that from whence the original speci- 

 men from Staithes, Yorkshire, in the York Museum, was collected. 



Isastr^ea Murchisoni, Wright, nov. sp. 



Corallum large, and very massive ; surface convex, and covered 

 with numerous concave cells. Calices unequal in size and form ; 

 the larger ones occupy the upper surface, and the smaller ones are 

 situated on the sides of the corallum. The calices are polygonal, 

 deep, and concave ; their sides are of unequal length, and are termi- 

 nated by a very thin mural edge ; an ordinary-sized calyx contains 

 thirty-six septa : in some of the smaller ones there are thirty, and in 

 some of the larger ones forty or more septa. The septal systems 

 appear to vary considerably ; but, as the calices are much covered 



