20 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



is shown to be exactly comparable to that of a normal 10-armed comatulid, excepting 

 only that the second postradial ossicle is not axillary; in fact it is duplicated by the 

 structure of the undivided postradial series figured by Carpenter in Antedon clemens; 

 while that of E. japonicus and its relatives is comparable to the structure of a 10- 

 armed comatulid beyond the costal axillary. 



The costals (IBr) are shown to be merely reduplications of the first two brachials 

 interpolated between the base of the free undivided arms and the radials, and evidence 

 that this is the case is found in Perometra diomedeae in which an elongated tubercle 

 occurs on the articulation between the elements of each of the pairs, in Tropiometra in 

 which the elements of both pairs are greatly and similarly enlarged, and in various 

 species of Charitometra and of Thalassometra in which the first two brachials and all the 

 pairs of ossicles between them and the radials are similarly ornamented. Division 

 series succeeding the costals are merely repetitions of them, and in division series of 

 4 (3+4) two pairs of ossicles are present instead of the more usual one. 



It happened that one of the radial articular faces of the specimen of Eudiocrinus 

 variegatus was exposed through the loss of an entire postradial series This was 

 found to be strikingly similar to the radial articular faces of Zygometra hartlaubi. 

 The radial articular faces of Pentametrocrinus japonicus, on the other hand, were 

 found to be entirely different and similar to those of Decametrocrinus, coming nearest 

 to those of certain genera of the Antedonidae, such as Thaumatometra and Psathyro- 

 metra, and the general character of the pinnules, arms, and cirri also suggests the same 

 relationship. 



Figures were given of the radial articular faces of Pentametrocrinus japonicus 

 (lateral and ventral views), Psathyrometra fragilis (lateral view), and Zygometra 

 hartlaubi (lateral and ventral views), of the proximal portion of an arm pair of Thau- 

 matometra tennis, of the proximal portion of the arms of Pentametrocrinus tuberculatus 

 and of Eudiocrinus variegatus, and of the lower pinnules on both sides of the arm 

 and of a cirrus of the last named. 



A detailed account of the Owston collection of comatulids was published on 

 July 1 5 ; the species included were : 



Comaster robustipinna. Thalassometra komachi. 



Comaster japonica. Charitometra distincta. 



Comaster parvicirra. Charitometra lata. 



Comaster imbricata. Calometra JJavopurpurea. 



Eudiocrinus variegatus. Calometra separata. 



Himerometra subcarinata. Calometra multicolor. 



Oligometra japonica. Tropiometra afra. 



Cyllometra albopurpurea Perometra diomedeae. 



Thalassometra orion. Erythrometra ruber. 



Thalassometra quinquecostata. Compsometra serrata. 



Thalassometra aster. Iridometra psyche. 



