POTERIOCRINID.E EXTRACRINUS. 97 



We have accorded to the late Mr. Miller the merit of establishing this species, for 

 although Mr. Parkinson and others had previously described it under the name of the 

 Briarean Pentacrinite, they had not attempted to place it in its true position among 

 crinoids, or to establish a systematic arrangement, by which alone the nature of animals 

 and their relative affinities can be properly understood. 



Synonomes and References. 



Briarean pentacrinite. — Park. Onj. Rem. tab. 17, fig. 15. — tab. 18. f. 1, 3. 



— Knorr. Recueil. de Mon. Suppl. tab. 11. f. 6. 



— Blumenb. Abbild. Nat. Gcg. 70, PL 1, / a and b. 

 Pentacrinites Britannicus.— Schloth, Petref. p. 328, Nachlr. 11, p. 10.5, tab. 30, y! 



\. a, to c. 

 Pentacrinites Briareus. — Mill. Nat. Hist. Crin. PL 1 and 2, pages 56 and 57. 



.— Goidf. Pet. Germ. PL 51, fig. 3 a, m. p. 168. 



.— Buckl. Bridg. Wat. Treat. VoL\. fig. 434, V VoL 2 p. 52 Sj- 53. 



. — Aust. Ann. and Mag. Nat. HisL VoL \0, p. 109. 



Formation and Localities. 



The lias at Lyme Regis ; Charmouth ; Watchet ; Horfield ; Keynsham ; Boll, 

 Wurtemburg. — Cornbrash, a sub-ordinate member of the oolitic sj'stem, at Kingscote 

 Turnpike. 



This species appeared at an early period of the lias, and attained to its greatest 

 diffusion before the liassic deposits terminated, its numbers then rapidly diminished 

 until it finally became extinct during the deposition of the lower oolite. 



Henry Sheppard, Esq. was the first to point out its existence in the Cornbrash. 



Description of the Calcareous Skeleton. 



The Dorso-central Plate, is small and composed of five pieces, it is so completely 

 concealed by the surrounding pieces that it can only be seen by looking into the interior 



N 



