34 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



Toward the ends of the arms they become shorter. The segments of the lowest 

 pinnules have small spines on their distal edges. The relative length of the proximal 

 pinnules is very variable. On the same specimen P 2 is sometimes longer than Pi, and 

 sometimes it is shorter, occasionally very small, and this is true of wholly comparable 

 arms, as for instance of arms from a IIBr axillary. This inconstancy holds for the 

 outer as well as for the inner arms. On many arms from a IIBr axillary Hartlaub 

 found all three of the lowest pinnules of the inner side (P a , P b , and P ) very small, 

 though sometimes they are of about the same length as the pinnules of the outer 

 side (P,, P 2 , and P 3 ). 



The pinnules have prominent side and covering plates. When viewed from the 

 ventral side of the pinnule the side plates appear to alternate with each other and to 

 form a continuous zigzag wall. 



The disk is strongly incised and is beset with irregularly distributed spines. Sac- 

 culi are numerous on the pinnules and very thick and crowded on the arms. The size 

 of the sacculi is proportionate to that of the underlying ossicles. 



The color in alcohol is brownish white, the arm bases sometimes somewhat darker. 

 The disk is bright brown with a reddish tinge. 



Hartlaub wrote that the two specimens from Montserrat in 88 fathoms (Blake 

 station 155) and two from St. Lucia in 278 fathoms (Investigator) differ so markedly 

 from the others that they may be regarded as representing a special variety for which 

 he proposed the name brevispina. According to him the special characters of var. 

 brevispina are: (1) Almost complete absence of the small sharp spines on the ossicles 

 of the division series; (2) markedly weak development of the pick-shaped spines on 

 the brachials; (3) much stronger development of the spines on the segments of the 

 lower pinnules; (4) more deeply saddle-shaped ossicles of the division series; (5) deeper 

 yellow-brown color, with a darker shading of the division series; and (6) more pentag- 

 onal and longer IBr axillaries. 



Regarding a very young specimen of which a figure had been prepared by Car- 

 penter, Hartlaub said he believed he had found it in the material sent him, although 

 it bore no label in Carpenter's hand and was much more fragmentary than the figure 

 showed. The specimen measures 6 mm. from the centrodorsal to the tip of the longest 

 arm stump. The cirri are broken off. 



Carpenter's figure, according to Hartlaub, is not correct in certain details. It 

 shows in the middle of the radial a strong longitudinal ridge which is not present; 

 instead, there are two small spines, one more proximal, the other more distal. A 

 fairly deep cleft between the centrodorsal and the radials is not once indicated although 

 in young, as in older, individuals such a cleft is commonly present and is fairly charac- 

 teristic of the species. 



In a very young specimen from Barbados there is a subradial cleft, and the radial 

 has a swelling on either side. The lateral swellings of two adjacent radials form a 

 sort of base against which the proximal end of the interradial ridge of the centrodorsal 

 rests. A similar interradial structure is found also in fully grown individuals. 



Carpenter's figure is further inexact in that the brachials are shown as smooth 

 whereas in the specimen spines are developed in many places. The spinosity in this 

 species appears very early, as is shown by other small specimens. On the side opposite 

 that shown in the figure a IIBr 2 series is developed, so that there are at least 11 arms. 



