248 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



and distally. A low crest runs along the outer surface of the pinnule which is at 

 first broad and well rounded but becomes sharp after the eighth segment. P 3 is 

 about 25 mm. long, with 35 or more segments, resembling P 2 and slightly, if at all, 

 stouter basally but tapering more gradually so that it is considerably stouter in the 

 outer portion. P 4 is 19 mm. long, with 26 segments, resembling P 2 but slightly less 

 slender and with longer segments distally. P 6 is 13 mm. long, with 26 segments, and 

 is less stout basally than the preceding pinnules. 



The preceding description is based upon a magnificent specimen from the Danish 

 Expedition to the Kei Islands station 72, which was originally described as a new 

 species under the name of Heterometra apollo but which does not appear to differ in 

 any essential feature from the specimens of H. quinduplicava previously known. 



Notes. The specimen from Albatross station 5355 is small with 18 arms about 80 

 mm. long and cirri from 20 to 22 mm. long. 



Carpenter described Antedon quinduplicava from Challenger station 212 as follows: 

 The centrodorsal is a thin disk with sloping sides. The cirri are about XVIII, 30. The 

 segments are tolerably equal ; the last few are rather compressed and faintly carinate, 

 and the penultimate bears a slight opposing spine. The radials are just visible. The 

 IBri are rather closely united, forming a median prominence (synarthrial tubercle) 

 with the pentagonal axillaries, and there is a similar but less marked prominence on 

 the first two segments beyond the axillary. The IIBr series are 4(3+4), and the IIIBr 

 series, when present, are 2. The 16 arms are about 80 mm. long. They are composed 

 of 150 or more smooth brachials of which all but the terminal are broader than long. 

 The lower brachials are subtriangular and the later ones are quadrate or almost oblong. 

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

 brachials 15+16, and distally at intervals of 5 to 11 (usually 8 or 9) muscular articu- 

 lations. P D is about equal to PI. P a is smaller again, while P 2 and P b are both longer 

 and stouter, reaching 11 mm., and are composed of about 18 smooth segments most of 

 which are longer than broad, and the lower are carinate. The pinnules of the next pair 

 are generally smaller again. But in arms arising from a IBr axillary P 3 and occasion- 

 ally P c may be large like those immediately preceding. The disk is 7 mm. in diameter, 

 naked and much incised. Sacculi are abundant. The color in alcohol is brownish 

 white with the perisome darker. 



Carpenter said that he had some doubts as to the propriety of separating this form 

 from Antedon anceps, which was found at the same station. The general characters of 

 the cirri, calyx, and large lower pinnules are the same in both types. One individual 

 of Antedon anceps has only 10 arms, but another has three and a third four IIBr 

 series. The outer parts of the arms are rather serrate, and P D is distinctly smaller than 

 PI. On the other hand, the two individuals he referred to quinduplicava each have 

 IIIBr series, nearly smooth arms with longer intersyzygial intervals, and P D of about 

 the same size as P^ 



Carpenter remarked that, considering the remarkable series of variations in 

 Heterometra crenulata, he thought it quite possible that we are here dealing with 

 another case of the same kind, but in the absence of the necessary intermediate links 

 he preferred to keep quinduplicava separate from anceps for the time being. He said 

 that the only species which approaches quinduplicava and anceps at all closely is 



