250 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



smaller number of stouter segments, several of which are considerably longer than 

 broad. The third pair (P 3 and P c ) are smaller again. The more distal pinnules of 

 each pair (that is, those on the inner side of the arm) are smaller than the more proxi- 

 mal ones (on the outer side of the arm). The pinnules of the eighth and following 

 brachials have slight dorsal keels on their lower segments. The disk is 7 mm. in 

 diameter, naked and rather incised. Sacculi are abundant on the pinnules. 



Carpenter said that on the undivided postradial series there is a pinnule on the 

 second ossicle, but none on the next. It is clear therefore that a IBr series is present, 

 but the IBr 2 is not axillary, as in the arms of the species of Eudiocrinus (see page 143). 

 One postradial series does not divide until the fourth ossicle beyond the radial, the 

 axillary being a "syzygial joint," and the second and third segments bear pinnules. 

 One of the IBr series is thus 5(4 + 5). In Carpenter's description the division of the 

 postradial series as described would give 10 arms, but the number of arms is said to 

 be 11. The mention in the discussion of the species of this aberrant IBr series cor- 

 rects this discrepancy. 



I examined the type specimen of Antedon clemens in the British Museum in 

 1910 and found that it most certainly represents the same species as the type specimen 

 of A. a/nceps. 



The specimen from Siboga station 99 has 26 arms 80 mm. long. Two of the 

 arms arise directly from IBr axillaries. There are eight IIBr 4(3+4) series each of 

 which bears internally a IIIBr 2 series. The cirri are XVIII, 27-30, 22 mm. long. 

 This example exactly resembles one from Albatross station 5139. 



The specimen from north of central Java is small. It has 16 arms and is under- 

 going adolescent autotomy. 



Of the two specimens recorded by Professor Koehler from Biliton, which were 

 in very bad condition, one has 12 and the other 13 arms. 



The specimen from the Danish Expedition to the Kei Islands station 103 is 

 smaller than that upon which the description of the species as given above is 

 based (from station 72) ; it has 23 arms 110 mm. long. Of the nine IIBr series present, 

 eight are 2 and one is 4(3+4). Three IIIBr series are present, of which two, both on 

 the same IIBr series, are of a single ossicle only, and one is 2. There is a single IVBr 2 

 series, developed internally on a IIIBr 1 series. The cirri are XX, 29-31, from 20 to 

 25 mm. long. 



The two specimens from Singapore have the arms about 60 mm. long. One has 

 21 arms, resulting from the presence of six IIBr 4(3 + 4) series and five IIIBr 2 series, 

 the latter all developed internally in 1, 2, 2, 1 order. The other specimen is similar. 

 These specimens agree in every way with others at hand from the Pliilippme Islands. 

 P D , though larger than usual in this genus, is nevertheless smaller than PI. 



The specimen from the Andaman Islands is immature with 14 arms about 100 

 mm. long. 



Radials. Carpenter found, by dissecting one of the two specimens that he 

 referred to Antedon quinduplicava, that each of the radial areas on the ventral surface 

 of the centrodorsal is marked at its proximal end by a large bilobate pit, so that every 

 two pits are separated by an interradial ridge. These pits seem to be nothing but 

 an unusual development of the radial pits that occur around the lip of the centrodorsal 

 in so many comatulids and receive the lower ends of the axial radial canals, and so 



