The Ceinoids feom Dr. S. Bock's Expedition to Japan 1!>U. I;{1 



ever, has a conical Cd, while the above-described species, like Toxo- 

 metra jjaupera^ has a discoidal one. {Iridometra has smooth arms and 

 at least 13 segments on Pj — P,.) — To the relation between the rela- 

 tive length of the proximal pinnules is, generally, attached a rather 

 great value in judging the genera within the Antedonid family. When 

 characterizing the genus Toxometra A. H. Claek says that P3 should 

 be the longest p. The case in question shows that one must be rather 

 cautious in using such a character as a generic mark. If my species 

 really belongs to Toxometra then P3 is the longest pinnule only in T. 

 paupera and may not be used as a mark of genus. A comparison 

 between the different species desci'ibed as 7', paupera shows, moreover, 

 that within this species too there is rather great vai'iability in the re- 

 lative length of the proximal pinnules. The largest specimen has Pj 

 15; 5,5 mm., Pg 16: 7,5 mm. and P3 22; 12 — 13 mm., the smallest one 

 with an arm-length of 80 mm. has Pj 12; 4,5 mm. Pg 14; 6 mm. P3 

 17; 7 — 7.5 mm. With shorter arms we therefore get a proportionally 

 greater abbreviation of P3 than of Pj and Pg within this species. (Cf, 

 p. 76). I have also demonstrated the same general rule concerning 

 P2 in Gyllometra pulchella. 



Nevertheless, because of the following facts, I have not thought 

 the specimens in the Bockian collection to be young forms of T. pau- 

 pera. 1) The cirrals are somewhat shorter than in the species men- 

 tioned (if we had been concerned with a young form, they ought to 

 be longer). 2) The distal pinnules are longer than in T. paupera when 

 compared with the arm-length. 3) The genital glands are rather well 

 developed. 4) The photo in the Siboga work shows that T. paupera, 

 though very much larger than T. a'quiplnua, has smaller prominences 

 on the Br-segments (if the last-mentioned species had been a young- 

 form, the condition ought to have been the reverse), and 5) the 

 geographical distribution is rather different, as T. paupera is only noted 

 from the Sunda Islands and the Philippines. 



