EEVISION OF PALEOZOIC STELLEROIDEA. 275 



fine-grained micaceous sandstone. It is named Crihellites carbo- 

 narius; and the following characters are observable: Rays five, 

 rounded, lanceolate, five times as long as the disk, ridged in the center, 

 covered with longitudinal rows of reticulating tubercles; disk small 

 and tuberculated. The disk is only 0.3 of an inch in diameter, 

 while the rays are 1.5 inches in length. A circular impression in the 

 disk may be the impression of the !Madreporiform nucleus. In the 

 form of this Asteroid, and in the characters observable, it is similar 

 to Crihella rosea, Miiller; but the rays are proportionally longer, the 

 disk smaller, and the tubercles much nearer to each other than in 

 the recent analogue. The sandstone from which the fossil Sea-star 

 was obtained lies 20 feet above the Shilbottle coal, and about 600 

 feet below the base of the miUstone grit, being in the upper part of 

 the Mountain Limestone formation, which, in Northumberland, is 

 about 3,000 feet in thickness. In this sandstone there also occur 

 Strophomcna crenistria and the remains of carboniferous plants." 



Order OPHIOCISTIA Sollas. 



Ophiocistia Sollas, Quart. Joum. Geol. Soc. London, vol. 55, 1899, pp. 692, 700. — 

 Sollas and Sollas, Philos. Trans. Roy. Soc. London, ser. B, vol. 202, 

 1912, pp. 214, 222. 



An anomalous order of free Echinoderma. 



"The Ophiocistia are Ophiuroidea with five paired series of append- 

 ages, proceeding from the ventral surface of a plated test; and in 

 which vertebral ossicles are absent or insignificant" (p. 700). 



Contains but one family, the Eucladiidse. 



Remarlcs. — That Eucladia and EutJiemon, the genera belonging to 

 this order, are ophiurids is said to be apparent from the foUowuig: 

 "The absence of any openings on the dorsal surface, and of any indi- 

 cation of an anus, the ventral position of the madreporite, and the 

 sharp distinction of the arms from the test." On the other hand, 

 they differ from all known ophiurids in several important particu- 

 lars: 



"The structure and disposition of the arms is unlike anything 

 known among either the Ophiurse or the Euryalaa, and finds no 

 parallel among any group of fossil Opniuroidca. If we consider the 

 disposition of the arms first, we find as a constant character among the 

 rest of the Ophiuroidea the extension of five of these appendages over 

 the ventral surface of the disk as far as the buccal aperture; the 

 vertebral ossicles of the arms are also serially represented in the 

 buccal armature. In the Eucladiidne also the arms are given off 

 from the ventral surface of the test, and the first pair have their 

 origin in the outer distal angle of the jaws; if, however, we are to 

 regard the serial arms of Eucladiida^ as the free extremities of lateral 



