ON THE ECHIXOIDEA. 459 



on a slab of Lower Lias, at Binton, in AVarvvickshire,* and in the White Lias at Stoney- 

 thorpe, in the same county. The rock at Binton which contained this urchin comes from 

 the base of the zone of Ammonites j^^cinorbis, and is known to the workmen as the 

 Guinea Bed. It contains the bones of Saurian reptiles, &c., with the shells of Avicula 

 longicostata, Stutch, Lima punctata. Sow., Ostrea liassica, Strick., and a small Coral. 

 It may be justly considered as one of the basement beds of the Lower Lias, and this 

 Hemipedina one of the earliest forms of the Diademad.e in the Liassic rocks. 



Pedina ^umnUy Forbes. Supplement, PL XLI, fig. ^a, b, c; PI. XLIII, fig. 1 a, b,c, d. 



See pages 176-178, 'Monograph.' 



PsEUDOPEDiNA NODOTi. Cotteau, Sevue et Magasin de Zoologie, No. ,5, 1858, pi. ii, 



figs. 4 — 7. 



Since I figured the original specimen of this species (PI. XIII, fig. 2), which was 

 collected by Dr. William Smith from the Inferior Oolite at Tucking Mill, I have met with 

 two specimens from the Inferior Oolite, near Cheltenham ; one from the Great Oolite 

 near Cirencester, and one from the Cornbrash at Islip, near Oxford. One of the Inferior 

 Oolite specimens was obtained from the Oolite marl near the Seven Springs, and is 

 figured in PI. XLI, fig. 2. The inter-ambulacral areas are very wide, and the })lates com- 

 posing them large; on the sides and upper surface there is only one row oi primary 

 tubercles situated very near the poriferous zones (fig. 2 b), and all the inter-tubercular 

 space is covered with very small granules. The ambulacral areas are narrow, and taper 

 much ; the tubercles are few in number, very small, and sparsely distributed on the upper 

 part of the area, but are larger and more numerous below. The proximity of the 

 primary tubercles to the poriferous zones, the narrowness of the ambulacra, and the 

 sparse distribution of tubercles thereon, with the wide space down the middle of the 

 inter-ambulacra, which is occupied entirely with small granules, produce a remarkable 

 physiognomy in this urchin. 



The specimen from Oxfordshire was discovered by Mr. Whiteaves in the Cornbrabh 

 at Islip, and was presented by him to the Oxford Museum. I have figured this beautiful 

 fossil in PI. XLIII, fig. 1 ; as it is much more depressed than the Inferior Oolite varieties, 

 although it evidently belongs to the same species ; the base is flat, the mouth-opening 

 large, and the peristome deeply divided by notches (fig. 1 b) ; the tubercles arc much 

 more abundant at the base (fig. 1 b), a second row occupying the middle of the inter-am- 



* The reader is referred for a detailed description of this section to the author's memoir, 'On the 

 Zone 0^ Jvicula contorfa, and the Lower Lias in the Soutli of Englr.nd.' " Q'lart. Journ. of tlie Geol. 

 Soc," vol. xvi, p. 394. 



CO 



