336 FOREIGN JURASSIC COLLYRITIDiE. 



CoLLYRiTES CASTANEA, Desor. Synopsis fles Echinides Fossiles, p. 207. 



" Test very much inflated, short, almost spherical, contracted and sub-rostrated pos- 

 teriorly ; posterior ambulacra much arched, and converging immediately above the vent, 

 which is only visible below ; inferior surface convex and undulated ; the ambulacra repose 

 in depressions, and the inter-ambulacra form convexities between them ; the single inter- 

 ambulacrum is very prominent." Desor. 



Formation. — "Kellovien de St.-Croix, de Poillerel pres Chaux-de-Fonds. Pas trop 

 rare.'^ 



Collections. — " Mus. Neuchatel, coll. of MM. Campiche, Nicolet.'' Desor. 



CoLLYRiTES VoLTZii, Agass. Syn, Disaster Voltzii, Agassiz. Echinodermes Foss. de la 

 Suisse, tab. iv, figs. 11 — 13. Desor, Monogr. des Disaster, tab. i, figs. 18 — 21. 



Test large, circular, depressed, convex above, flat below ; posterior ambulacra very 

 much arched and converging above the vent, which is large, pyriform, and infra-marginal ; 

 mouth-opening central ; peristome circular ; base nearly flat, and only slightly cushioned ; 

 the ambulacra lie in depressions, and the inter-ambulacra form inconsiderable convex 

 prominences ; the ambulacra are all equal in width, and there is no anteal sulcus ; the 

 pores are closely approximated, and form double rows near the peristome. 



Formation. — ''Oxfordien des Voirons pres Geneve. (Voltz)." 



Collection. — Museum of Strasbourg. Very rare ; only two specimens known, both 

 of which are in this Museum. One of them measures 3^ inches in 

 diameter. 



CoLLYRiTEs TRANSVERSA, iVOrhiguy. Paleoutologie Fran^aise Ter. Cretaces. p. 50. 



A large species, sixty-one millimetres in breadth. Under this name M. d'Orbigny 

 notices a cordiform species, the length of which is only nine tenths of its breadth, and is 

 as high as it is long. This species is remarkable for its transverse form, its nearly round 

 figure, and deep anteal sulcus. 



