A MONOGRAPH OF THE EXISTING CRINOIDS 223 



as broad as long with the lateral borders about two-thirds as long as those of the IBr 1( 

 in the midline about twice as long as the IBr^ the two distal sides are concave. A 

 rather abrupt broad rounded median keel resembling that on the IBr t runs their entire 

 length. The IIBr series are 2 and resemble the IBr series. 



The 11 arms are 65 mm. long. The first two brachials are similar, slightly longer 

 exteriorly than interiorly, about four times as broad as long. They have raised rounded 

 median keels resembling those on the division series. The first syzygial pair (composed 

 of brachials 3 + 4) is about two and one-half times as broad as long and oblong; the 

 distal edge of the hypozygal is prominent so that the syzygial pah- has the appearance 

 of two short brachials. The next five brachials are slightly wedge-shaped, about three 

 times as broad as long. The tenth brachial is oblong. The brachials following the 

 tenth are very obliquely wedge-shaped, somewhat longer than broad, the proportions 

 remaining fairly uniform to the arm tips. Each brachial has a rather broad low raised 

 median line which in the distal portion of the arm gradually becomes obsolete. The 

 division series and first two brachials are in close lateral apposition and are sharply 

 flattened against each other, the flattened surface rapidly decreasing in width from 

 the IBr! on which it is about three times as broad as long to the second brachial on 

 which it is only as broad as the pinnule base. 



Syzygies occur between brachials 3+4, again from between brachials 11 + 12 to 

 between brachials 15 + 16 (usually between brachials 14+15), and distally at intervals 

 of from 6 to 1 1 (usually 6 or 7) muscular articulations. 



PI is 6 mm. long, rather slender, and tapering evenly and slowly to a rather delicate 

 tip. It is composed of 20 segments all of which are somewhat broader than long. 

 The first segment is about twice as broad as long, broadly crescentic with the outer end 

 rounded and the inner end truncated. The next two segments are roughly oblong, 

 and those following have the proximal border broadly and evenly rounded and the distal 

 border straight or slightly concave. 



P 2 is 5.5 mm. long with 17 segments. It tapers more slowly than PI and hence 

 appears somewhat stouter in the distal half, and the segments are more nearly oblong, 

 on the last ten becoming about as long as broad. 



P 3 is 5.5 mm. long with 13 segments resembling P 2 but somewhat stouter. 



The genital pinnules are from 3 to 4 mm. long with from 9 to 12 segments. The 

 first segment is crescentic, twice as broad as long, the second is trapezoidal, nearly as 

 long as broad, and those following are oblong, somewhat longer than broad. The two 

 terminal are small. In the shorter genital pinnules the third and fourth segments are 

 markedly longer and slightly broader than those following, though they are not broader 

 than the two basal segments; the third segment is about half again as long as broad or a 

 little longer, the fourth is twice as long as broad, and the fifth is slightly longer than broad. 



The distal pinnules are 5 mm. long with 13 or 14 segments, of which all but the two 

 basal and the terminal are about one-tliird again as long as broad. 



Notes. There appears to be no doubt that Antedon garrettiana, very inadequately 

 described in 1907, was based upon an immature individual of the species described and 

 figured by Gislen in 1922 under the name of Diodontometra bocki, which in 1927 he 

 recorded from Mortensen's station 9, near the type locality of garrettiana. 



The centrodorsal of the type specimen of garrettiana and the arrangement of thecirrus 

 sockets are very closely similar to the same features figured by Gislen in a specimen from 



