348 PROCEEDINGS OP TIIE ACADEMY OP [1885. 



ficially resembles a Blastoid. However, with the arms removed, 

 it is found to possess all the essential characters of the Actino- 

 crinidse, and doubts might be entertained whether it should not 

 be grouped with that family. Angelin and Zittel have made it 

 the type of a distinct family, and we think the peculiar construc- 

 tion of the arms and ventral side fully justifies this separation. 

 The arms of Barrandeocrinus i if we correctly understand the fig- 

 ures, were permanently in a recumbent state or moved with great 

 difficulty ; they were laterally connected at the tips of their pin- 

 nules, at least those of the same ray, and could not be closed in 

 the usual way. 



Generic Diagnosis. — In its general outline, with the arms at- 

 tached, resembling a Blastoid ; form globose; calyx, without arms, 

 cup-shaped. Arms arranged in pairs; recumbent; their dorsal 

 side directed toward the calyx, the ventral side exposed to view. 

 They are united laterally by the tips of their pinnules so as to 

 completely cover the calyx, and extend beyond it to the upper 

 part of the column, which is somewhat indented for their reception. 



Basals three, equal. Primary radials (?) 3 X 5, 1 the first con- 

 siderably larger. The axillary radials support at each upper side 

 a single rather large secondary radial, and these support an arm 

 each. Interradials arranged as in the Actinocrinidae ; the four 

 regular sides, up to the aims, consisting of oi\\y one plate, which 

 rests upon the first radials. The axygous side has two large 

 anal plates ; the lower one meeting the basals, the other placed 

 between the interradial which is bisected for its reception. These 

 are succeeded by three much smaller and elongate interradial 

 plates, and a similar number of interaxillary pieces of exactly the 

 same form and arrangement as the three interradial ones. Ven- 

 tral surface deeply depressed along interradial and interaxillary 

 spaces, the depressions which grow deeper toward the equatorial 

 zone alternating with ten flattened ridges which led to the ten arms. 



Arms heavy ; composed of a single row of closely set, quad- 



1 Angelin slates that the number of radials is 2X5, while Zittel gives it 

 as 3 X 5. In Angelin's figure. Icon. Suec., PI. v, figs. G, 6 a, there appear 

 to be but two primary radials, the second plate being axillary. But in the 

 specimens represented on PI. iv., fig. 5 a, and PI. xxii, fig. 3, three of them 

 ar^' visible, arranged as those of Actinocrinus. It is probable that the true 

 number is three, and that in the first mentioned specimen 1 he sutures be- 

 tween the sccoud and third radials became obliterated by anchylosis. 



