A MONOGRAPH OF THE EXISTING CRINOIDS 175 



brachials are covered with numerous and thick-set very fine spines which become less 

 apparent after about the tenth brachial, at which point the brachials develop an over- 

 lapping border of very fine teeth and longitudinal striations, the latter on the distal 

 brachials becoming more pronounced and on the outer portion of the brachials breaking 

 up into numerous fine spines. 



Syzygies occur between brachials 3 + 4, again between about brachials 15+16, and 

 distally at intervals of from 3 to 5 muscular articulations. 



Pi 7 mm. long with 21 or more short segments of which the basal 4 or 5 are produced 

 dorsally into a broad thin keel; all the segments have their edges armed with tufts of 

 very fine spines. P 2 is 5 mm. long with 16 segments of which the basal 3 or 4 have a 

 thin dorsal keel which, however, is not nearly so wide as that on the preceding pinnule. 

 P! and P 2 are somewhat flattened laterally. The three following pinnules are in general 

 similar to P 2 but more slender. The pinnules of the next 3 or 4 pairs have the third-sixth 

 segments laterally expanded as a cover to the gonads, after which the pinnules become 

 slender and more elongated, reaching a length of 8 mm. with 15 segments. 



After examining the type specimen of Antedon gracilis in the British Museum Prof. 

 Torsen Gislen said that gracilis is close to hirsuia and pubescens, and probably all three 

 will turn out to belong to one species. 



Localities. — Challenger station 214; off the Meangis Islands, southeast of Mindano, 

 Philippines (lat. 4°33' N., long. 127°06' E.); 914 meters; bottom temperature 5.4° C; 

 blud mud; February 10, 1875 [P. H. Carpenter, 1888; Hartlaub, 1895; A. H. Clark, 

 1907, 1908, 1909, 1912, 1913, 1918; Gislen, 1928] (4, B. M.). 



Albatross station 4919; Eastern Sea, about 90 miles west-southwest of Kagoshima 

 Gulf, Japan; Kusakaki Jima bearing N. 18° E., 17.6 miles distant (lat. 30°34'00" N., 

 long. 129°19'30" E.); 804 meters; bottom temperature 5.4° C; globigerina ooze; 

 August 13, 1906 [A. H. Clark, 1907, 1908, 1909, 1912, 1915, 1918; Gislen, 1928] (2, 

 U.S.N.M., 22631, 35590). 



History. — Antedon gracilis was described and figured by Dr. P. H. Carpenter in 

 his report upon the comatulids of the Challenger expedition published in 1888; his ma- 

 terial consisted of five specimens from station 214, off the Meangis Islands in 500 fath- 

 oms. In 1895 Dr. Clemens Hartlaub discussed the systematic and bathymetrical 

 relationships of Antedon gracilis. 



In 1907 I described Antedon pubescens from two specimens from Albatross station 

 4919. In my first revision of the old genus Antedon published later in 1907 I listed 

 Thalassometra pubescens and also Thalassometra pergracilis, explaining that the latter 

 was a "new name for Antedon gracilis P. H. Carpenter, 1888, preoccupied (cf. Antedon 

 gracilis de Loriol, 1886)"; this was repeated in 1908. In 1908 Thalassometra pubescens 

 was listed as one of the crinoids occurring off southern Japan, and in two other papers 

 it was said to belong to a group characteristic of the oceanic fauna. In 1909 in my 

 revision of the family Thalassometridae pergracilis and pubescens were listed as species 

 of the genus Thalassometra, and in another paper published in the same year Thalasso- 

 metra pergracilis was compared with a new species, Th. attenuata. In a paper published 

 in 1912 it was compared with another new species, Th,. perplexa. In my memoir on the 

 crinoids of the Indian Ocean published in 1912 Thalassometra pergracilis was recorded 

 from about 30 miles west of Middle Andaman in about 485 fathoms, and notes were 

 given on the specimen; Th. pubescens was listed, and the synonymy and range were 



