1914 120 F. A. Bather — Studies in Edrioasteroidea. 



integument, shows that the theca as a whole was not particularly 

 flexible. 



On the Adoral or Upper Face are the five Eadial Grooves, of which 

 the course may first be traced in specimen A (PI. X, Fig. 1). All 

 proceed with a very slight curve to a distance of about 15 mm. from 

 the oral pole. The antero -lateral and postero-lateral rays have the 

 concave side of this curve turned towards the postero-lateral interradii ; 

 in other words the rays of the right-hand pair and of the left-hand pair 

 respectively bend towards each other. In the anterior ray the 

 concavity faces the right. That is to say, the proximal curve of the 

 left posterior, anterior, and right anterior rays (I, III, IV) is solar 

 or dextral, and that of the left anterior and right posterior rays 

 (II, V) is contrasolar or sinistral. All the rays except the right 

 posterior then suddenly bend in a contrasolar direction, and after 

 bordering the periphery for the space of an interradius, pass on to 

 the under surface of the theca, where they continue in the same 

 direction for the further space of an interradius, ending near the 

 adjacent ray (PI. X, Fig. 3). The only exception to this regularity 

 of these four rays is that the peripheral tract of the right anterior 

 ray bends upwards for a short distance within the right anterior 

 interradius (PI. X, Fig. 1). The right posterior ray, however, bends 

 in a solar direction, and returns on the posterior interradius, ending 

 on the oral face at a point a little to the right of the periproct, and 

 about 9*5 mm. from the oral pole (PI. X, Fig. 1). In consequence 

 of this, the peripheral tract of the left posterior ray passes across both 

 the posterior and the right posterior interradii, and ends against the 

 right anterior groove (PI. X, Fig. 2). 



The varying curves of the rays in this specimen A and their sharp 

 definition give them a peculiar aspect of independent life. The 

 width of a ray in the proximal half of its course is 5*5 mm., or slightly 

 less when close to the peristome ; where it bends, the width is 

 4*5 mm. ; on the under side it gradually tapers to 3 mm., after which 

 it is rapidly rounded off. 



In specimen B the general shape and disposition of the rays is 

 precisely as in A, except that the anterior ray does not begin with 

 a solar curve, but runs straight to the main contrasolar flexure. The 

 width of a groove in the proximal half is about 6"3 mm., but may be 

 reduced to as little as 5*5 mm. at the bend (Plate XI). 



In specimen C the adoral region is covered with matrix, but from 

 the marginal tracts it can be inferred that the general disposition 

 of the rays is as in A and B (Plate XIII). 



Specimen E 16172, so far as preserved, indicates a similar 

 arrangement. 



In E 15930 the proximal curve of the rays is contrasolar in the left 

 posterior, left anterior, and right posterior (I, II, V), and solar in the 

 other two rays. The distal curve of the left posterior, left anterior, 

 and right anterior rays is visible on the under side of the theca and 

 is contrasolar (Plate XIV). Probably the general arrangement was 

 as in A. 



E 16054 is a young individual, as shown not merely by its small 

 size, but by the small extent of the periphery occupied by the distal 



