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IV.— ON A NEW SPECIES OF OROPHOCRINUS (PENTBE- 

 MITES), IN CABBONIFEKOUS LIMESTONE, COUNTY 

 DUBLIN. ALSO BEMABKS UPON CODASTER TRI- 

 LOBATUS (M'COY), FBOM CABBONIFEBOUS LIME- 

 STONE, COUNTY KILKENNY. By WILLIAM HELLIEB 

 BAILY, F.L.S., Etc. (Plate I.) 



[Bead, February 16, 1885.] 



Orophocrinus (Pentremites) pr^longus (n. s.) : 



This Blastoid is remarkable for its size and elongated charac- 

 ter, compared with others of the genus. 



Its general outline is that of a lanceolate body (calyx), with a 

 pentagonal summit, its greatest diameter being at the termination 

 of the ambulacra eight-tenths of an inch from the summit, decreas- 

 ing regularly towards the base and terminating obtusely, without 

 any trace of stem. 



The basal plates, conical in shape, extend upwards to about 

 one-third of its length, measuring nine-tenths by seven-tenths of an 

 inch; the radial plates are oblong, one inch and a-half by three- 

 quarters of an inch at the widest part ; the deltoid plates are small 

 and triangular, extending only to about three-tenths of an inch from 

 the summit, the five plates forming a pentagon when viewed from 

 above. 



The ambulacra are narrower than in 0. inflatus; the small plates 

 composing each are arranged in two alternating series, with a deep 

 groove down the centre, and are inclined towards each other at an 

 angle of about 15° ; there are sixteen of these plates in the space 

 of a quarter of an inch. 



The mouth, which was small and central, and ovarian apertures 

 are not sufficiently well shown for description. 



Length, two inches and five-tenths; breadth at widest part, 

 one inch and six-tenths. 



Plate i., figs. 1, 1a, 2, 2a, 2b. 



Localities. — St. Doolagh's and Eaheny, Co. Dublin, in lower 

 carboniferous limestone ; collection, Geological Survey of Ireland. 



