150 



MESSES. G, SHAEMAN AND E. T. NEWTON 



13. On a NEW eoem of Agelaceinites (Lepidodiscus Milleri, 

 Qi. sp.) from the Lower Caebonieerods Limestone of Citmbee- 

 LAND. By G. Sharman, Esq., and E. T. Newton, Esq., E.G.S. 

 (Eead January 6th, 1892.) 



[Communicated by permission of tiie Director-Greneral of the 

 Geological Survey.] 



[Plate II.] 



DuEiNG the Geological Survey of parts of Cumberland and North- 

 umberland (Sheet 106, N.W.) by Mr. Hugh Miller, a large series 

 of fossils was obtained by the Survey collector, Mr. J. Rhodes, from 

 the Lower Carboniferous rocks ; and among them are two referable 

 to that rare and interesting group of Echinoderms, the Agelacrini- 

 tidae. The only representatives of this group hitherto recorded 

 from British deposits are Agelacrinites Bucliianus, from the Bala 

 Beds, described by Eorbes,^ and Lepidodiscus Lehouri^ from the 

 Carboniferous Limestone, described by Mr. Percy Sladen f our 

 specimens are evidently closely related to the latter species. It is 

 very desirable that some account of such rare fossils should be placed 

 on record, more especially as we believe them to represent a new 

 species. 



Both the specimens are attached to valves of Myalina, and both 

 are from the Biver Irthing ; but one is from near Lamport, on the 

 Northumberland side of the river, and the other from near Water- 

 head, on the Cumberland side. The example from Lamport is too 

 imperfect for description, but that from AYaterhead is in a very 

 perfect state of preservation, and is alone alluded to in the following 

 remarks. The test is extremely flat, and forms an almost circular 

 disc about -^ inch (1 centim.) in diameter. There is a distinct 

 marginal zone, the width of which is about one fifth of the diameter 

 of the entire test. Five rays or arms radiate from near the centre, 

 curving outwards towards the circumference ; but they end at the 

 inner edge of the marginal zone, and do not extend along this 

 margin for any appreciable distance. The curve of one arm is 

 reversed, so that the two which surround the pyramid are turned 

 towards each other, and the interradial space thus enclosed is some- 

 what larger than any of the others. The arrangement of the 

 median arm-ossicles is not very distinct ; but for the most part they 

 appear to be wedge-shaped, and though iiiterlocking do not reach 

 quite across the arm, though it is possible that some may do so. 



The pyramid is well shown ; it is placed in the middle of its 

 interradial space, and apparently possesses 9 or 10 triangular 

 plates. 



The scale-like plates, with which the surface of the test is 

 covered, are imbricated, and ornamented with microscopic granules, 



1 Mem. G-eol. Surv. vol. ii. (1848) part ii. p. 521. 

 - Quart. Jo urn. Geol. Soc. vol. xxxv. (1879) p. 744. 



