A MONOGRAPH OF THE EXISTING CRINOIDS 145 



which resembles the pmnules preceding, and P7 and the following pinnules are stouter 

 still, though slender in the distal half. This stoutness persists in the succeeding pin- 

 nules, though in the distal pinnules it is less in extent, occupying only about one- 

 third of their length. The genital pinnules are about 6 or 7 mm. long, stout basally 

 but evenly tapering and becoming slender in the distal half. They are composed of 

 16 segments, of which the first 3 are twice as broad as long, the fourth is somewhat 

 smaller and proportionately slightly longer, the fifth or si.xth is about as long as 

 broad, and the distal are more than twice as long as broad. The distal pinnules are 

 10 mm. long, with the basal segments large, much broader than long, and those fol- 

 lowing becoming gradually narrower and proportionately shorter, after the fifth or 

 sixth about as long as broad, and slender and rather more than twice as long as broad 

 distally. The surface of the pinnule segments is rough, and the ends are always 

 more or less spinous. The distal dorsal surface is usually studded with small spines, 

 but is never produced or carinate. 

 The color in alcohol is white. 



Notes. — Hartlaub remarked that all the specimens belonging to the variety 

 alata have rather slender cirri. 



He further noticed that the amoimt of eversion of the distal ends of the brachials 

 is variable, and that all intergradations are to be found between specimens with very 

 high processes on the lower brachials and those with smooth arms. Also there are 

 many intergrades between individuals with broad and stout arms and those with 

 narrow and slender arms. 



In alata the brachials are more closely united than in pulchella, or than in the 

 variety called by Hartlaub planata. Except for the everted processes standing up 

 at right angles to the axis of the arm, the brachial articulations are smooth. These 

 everted processes occupy a sharply delimited region on the distal border of the 

 brachials; only very rarely do they pass gradually onto the sides so that the rest of 

 the edge of the brachial is roughened. 



A feature which Hartlaub considered as especially characteristic of alata is the 

 commonly observed broadening of the arms toward the middle, although in this 

 exceptions occur. In many specimens the arms are at first very narrow, but toward 

 the middle they broaden to a most extraordinary degree. This has a pronounced 

 effect on the general appearance of the animal. 



In alata the position of the syzygies varies in different individuals quite as nmch 

 as in pulchella. In some the intersyzygial interval is from 12 to 14 muscular articu- 

 lations, while in others it is from 3 to 6. 



In alata Hartlaub found that the division series are free laterally, the only excep- 

 tion being a single 19-armed specimen from Blake station 269, in which in one place 

 the IBrj (axillaries) are in close lateral contact. 



A complete absence of IIBr series is rare. In all the material belonging to species 

 of the genus Neocomatella studied by Hartlaub he found only 13 siich cases, including 

 one the identification of which was uncertain. Of these 13 specimens, 5 belonged to 

 alata; in 3 of these the characters were strongly marked, in the other 2 they were 

 intermediate. It thus follows that in alata, of which Hartlaub studied 11 typical and 

 6 intermediate specimens, the percentage of 10-armed individuals is higher than in 

 pulchella. 



