30 CIDARIS. 



spines in situ on the slab. Like the specimen we have figured, it lies crushed upon its 

 upper surface ; the mouth-opening contains some of the jaws and teeth. A crushed 

 Cidaris, on a slab of Lower Lias shale, from Brockeridge Common, Gloucestershire, 

 has been communicated by Professor Buckman. The areolas in this specimen are 

 oblong, and some of them are entirely surrounded by a scrobicular circle of small, close- 

 set granules, whilst a few only are confluent. The character of the bosses, however, with 

 their flat, deeply-crenulated summits, and small, perforated tubercles, convince me that 

 it is Cidaris Edwardsii. Had a doubt existed, it would have been removed by the 

 discovery of one of the primary spines laid along the concealed portion of the test, 

 which exhibited the crenulated head and milled neck, with longitudinal lines, so very 

 characteristic of this Middle Lias urchin. The entire confluence of the areolas in the 

 large specimen may prove to be an adult character ; as the crowding together of so many 

 tubercles in each column of tubercular plates, may have necessitated the absorption of 

 a portion of the scrobicular circles, which existed in juvenile individuals. On this 

 interesting slab there are two separate vertebrae of an Ichthyosaurus. Professor Phillips, in 

 his 'Geology of Yorkshire,' figures a spine, PI. XIII, fig. 17, which resembles those of 

 our urchin, but its characters are not given in detail. Goldfuss* mentions spines, which 

 he erroneously referred to Cidaris Blumenbachii, that were collected from the " Gryphi- 

 tenkalke der Lias-Formationen bei Pretzfeld mid Theta, und ist der einzige Echinit, der 

 in Baiern dieser Formation angehort." One of the " aculeorum varise formre fragmenta" 

 (i, fig. 4, PI. XXXIX) so very much resembles the spines attached to the test of Cidaris 

 Edwardsii, that it is possible it may be the same. Quenstedtf has found spines in the 

 Lias, "am Donau-Mainkanal bei Dorlbach," one of which (PI. XLVIII, fig. 30) resembles 

 those of our species. Another spine, from the Inferior Lias of Dasslingen, Wurtemberg 

 (figs. 31, 32), has fine longitudinal lines, with small wart-like eminences, not arranged in 

 rows. All these Liassic urchins present nearly allied characters, and prove that Cidarites, 

 belonging to the same natural group, and if not to the same-, at least to allied species 

 of the genus Cidaris, lived over an extensive area during the deposition of the upper 

 shaly beds of the Lower Lias, or the Middle Lias of Continental geologists. 



In the Scarborough Museum I found a beautiful specimen of this species, with many 

 spines attached, as large as the one figured in this Monograph. It was collected from 

 the Middle Lias*of the Yorkshire coast. 



This species is dedicated to Professor Milne Edwards, of the Museum of Natural 

 History at the Jardin des Plantes, Paris. 



* ' Petrefacta Germanise,' vol. i, p. 11", tab. 39, fig. 4 c — k. 



t ' Handbuch der Petrefaktcnkunde,' p. 5/4, pi. 48, figs. 28 — 32. 



