366 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



Diagnostic features. The cirri are short and stout with the longest segments little, 

 if any, longer than broad and not constricted centrally; the expanded portion of the 

 genital pinnules is preceded by two unmodified segments so that it appears sessile; 

 the pinnules on the proximal portion of the arms are smooth or nearly so; PI is 6 mm. 

 long with 20-22 segments; the arms are 60-75 mm. long; and the cirri have 11-15 

 segments. 



Description. The centrodorsal is discoidal. According to the figure the cirri 

 are arranged in a partially double marginal row. 



The cirri are about XV, about 15; the segments are stout, the fifth and sixth slightly 

 longer than broad. 



Carpenter says that minute plates, probably the basal rays, rest upon the inter- 

 radial angles of the centrodorsal and separate the IBri. 



The IBri are nearly oblong, and are in close lateral contact beyond the ends of the 

 basal rays. The IBr 2 (axillaries) are short and broad with very open angles and are in 

 close apposition. Both the elements of the IBr series have traces of a median keel 

 which is continued on to the arm bases. 



The 10 arms are probably 60 mm. long. The first brachials are nearly oblong, with 

 the outer sides flattened. The inner sides of the second and third (hypozygal) brachials 

 are also flattened. The brachials after the eighth are triangular, at first considerably 

 broader than long, but gradually becoming more nearly as long as broad, and finally 

 wedge-shaped. 



Syzygies occur between brachials 3+4, again from between brachials 9 + 10 to 

 between brachials 13 + 14, and the distal intersyzygial interval is from 6 to 10 muscular 

 articulations. 



PI and P a are relatively small and are of tolerably equal size, with little more than 

 12 short segments. P 2 and P b have longer segments, and the pinnules of the seventh 

 and following brachials have the third and next two or three segments considerably 

 expanded so as to enclose the gonads, which are also protected by plates. The fourth 

 segment is larger than the rest, but not markedly so. 



The disk is 4 mm. in diameter. The disk and arms are distinctly, though not 

 extensively, plated. The pinnule ambulacra have fairly defined side plates with inter- 

 vening sacculi, which are also abundant in the plating over the gonads. 



The color in alcohol is white. 



Notes. Carpenter said that in his specimen PI is relatively shorter and much 

 less flagellate than in Glyptometra tuberosa, consisting of a smaller number of segments 

 and having an altogether stiffer appearance. 



In a specimen at hand P! is 6 mm. long with 20-22 segments; it tapers rapidly in 

 the first six segments and is very slender from the seventh segment onward. It is 

 possible that in Carpenter's specimen PI and P a were broken. In the present specimen 

 P 2 is about as long as P! with 13 segments; it tapers evenly from the base to the tip and 

 because of this appears considerably stouter than PI. The genital pinnules have the 

 third-fifth segments much expanded. The pinnule segments are without produced 

 and prominent distal ends. The arms are faintly carinate. None of the cirrus seg- 

 ments are longer than broad. 



After examining the type specimen in the British Museum I wrote that this species 

 is closely related to S. hepburniana; it is a large form with much less expanded genital 



