no. 1756. 



A NEW GENUS OF RFf'FXT CRIXGWK— CLARK. 



389 



nil I 



Basals 5, equal in size, broadly pentagonal, •">.<» mm. broa 

 3.7 nun. high, the anterior apex forming an 

 angle of about 120° (fig. 1): the basal circlet has 

 a diameter of about (i.4 mm.; its outer sides 

 are parallel with the dorso-ventral axis of the 

 animal. 



Radials large, trapezoidal, the dorsal surface 

 7.5 mm. long and 9 mm. in maximum (distal) 

 width: the outer sides of the radial circlet make 

 an angle of about 45° with the dorso-ventral 

 axis of the animal. 



The primibrachs are very closely united, ap- 

 parently by syzygy; the first primibrach occu- 

 pies proximally the entire distal border of the 

 radials: it is approximately oblong, with moder- 

 ately concave distal and convex proximal edges, 

 and straight lateral edges which are entirely free, 

 but are in close apposition with those of the neigh- 

 boring first primibrachs, and are sharply flattened . 

 The median length is -3.7 mm., the lateral length 

 3.5 mm.; the second primibrach (axillary) is con- 

 siderably smaller than the first, but of equal width ; 

 it is 3.3 mm. in median and 2 mm. in lateral 

 length; the anterior angle is rather obtuse; the 

 outer edges of the primibrachs are parallel with 

 the dorso-ventral axis of the animal. 



The secundibrachs are two in number, united 

 by syzygy like the primibrachs ; the first is much 

 largerthan the second, and is in close apposition 

 with its fellow interiorly, though not united 

 to it, 



The twenty arms are 1 55 mm. long, moderately 

 slender; the first brachial is large, approximately 

 square in external view; the second brachial is 

 united to the first by syzygy; it is oblong, about 

 twice as broad as long, and about one-half the 

 size of the first; the following brachials are ap- 

 proximately square, with concave sides and 

 slightly projecting and spinous distal ends, be- 

 coming longer than broad distally; the terminal 

 ten or twelve brachials bear no pinnules. There 

 are no brachial syzygies. 



The pinnules are not very different from those 

 of the pentacrinites, but the lower segments 

 have produced and strongly denticulate edges, this dying away 



B 



Fig. 2. -Proisocrdtos ru- 



1.1 i.KIMI -; PROXIM VI, AND 

 DISTAL PORTION OF COLUMN. 



