CARBONIFEROUS FOSSILS OF IRELAND. 183 



The column of this abundant species is round, formed near the pelvis of thin joints, alternately a little 

 longer and thicker, every third or fourth joint larger; nearer the base the joints become of an uniform thick- 

 ness and size; when young they are contracted at the sutures, so as to be slightly moniliform; the articulating 

 surface is regularly striated from the centre ; round, auxiliary side-arms come off irregularly from the columns ; 

 the plates of the body generally exhibit very distinctly the marks of muscular contraction, in the form of strong, 

 variable, radiating ridges. The fingers are formed, as usual, of two series of joints. Length of body from the 

 scapuliE one Inch, width one inch three lines. 



Phillipsocrinus. M' Coy. 



Gen. Ch. — Pelvis saucer-shaped, composed of one pentagonal and three hexagonal plates; supporting one 

 pentagonal and six hexagonal first costal plates; five of which, having their superior margins truncated, support 

 five scapuhe ; the pentagonal costal and one of the hexagonal costals, having their upper margin angularly 

 pointed, support no scapulas ; between each of the scapula; Is Interposed a single hexagonal, interscapulary plate, 

 but over the pentagonal costal, and over the hexagonal one with the pointed summit, two of them adhere 

 laterally together. 



This genus difters from all others of the tribe. In the great number of the costal plates ; It approaches most 

 nearly to the genus Caryocrinites of Say, from which It diflirs in the form of the plates of the pelvis ; that 

 genus has but six costals, this has seven ; In Cari/ocrinites, four of the costals are pentagonal, and two hexa- 

 gonal; In the present genus there are six hexagonal, and but one pentagonal; in Phillipsocrinus, there are 

 seven Interscapulary plates, and but five arms, while In Curi/ocrinus there are but two Interscapulary plates, and 

 there are six arms. Only one species Is as yet known. I have dedicated the genus to Professor Phillips. 



Phillipsocrinus caetocrinoides. M'Coy. (PI. XXVI. fig. 5). 



As but one species Is known, the generic characters above given will Identify it ; it will be only necessary 

 to add, that the plates exhibit the marks of strong, muscular contraction, as In Actiiiocrinus, between which 

 the surface Is minutely and Irregularly, but beautifully sculptured. Length from scapulas eight lines, width one 

 Inch. 



Atocrinus'. M'-Coy. 



Gen. Ch. — Column composed of round joints, alternately thicker and thinner; pelvis and entire visceral 

 cavity composed of one undivided piece, from which proceed five arms of one cuneiform joint, each supporting 

 two hands, composed of one cylindrical, and one cuneiform joint, each; one hand of each arm having three 

 fingers and the other but two, the fingers composed of a single row of joints. 



The genus Atucrinus has been formed for the reception of a little Crinoid, having the remarkable cha- 

 racter of an undivided cup, the plates of the pelvis, scapulas, &c. being all anchylosed (In Symbuthocrimis, Phil., 

 it is the pelvic plates only which are anchylosed). The fingers are thick, tapering but slightly, and composed 

 of but one series of joints, the hands are equal, one having two fingers and the other three. 



Atocrinus Milleri. M'Coy. (PI. XXV. fig. 20). 



Having had an opportunity of examining only one specimen of the genus, the above character will, at the 

 same time, indicate the only known species. Three of the joints nearest the pelvis are rather smaller than the 

 rest, and imlform in size; the cup Is hemispherical, a little dilated at the Insertion of the cuneiform arm joint, 

 surface smooth. Length from the pelvis to the tip of the finger seven lines. 



* a, privative, — r/fti'fti, seco, from its undivided cup. 



