72 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



DETAILS OF ARM STRUCTURE 



In his report upon a mass of dissociated comatulid ossicles from the Eocene 

 (Middle Jacksonian) at Baldock, Barnwell County, S. C., Professor Gisle"n took 

 occasion to classify the types of arm ramification found in the comatulids, both recent 

 and fossil. He distinguished 85 types, which he analyzed in detail on the basis of 

 available data taken from previously recorded specimens. He also reviewed with 

 great care such of the structural features of the Himerometridae as would be of 

 importance in the determination of dissociated fragments. 



From these dissociated ossicles he reconstructed Himerometra bassleri, sp. 

 nov., most closely related to the recent H. persica, which is interesting in being the 

 only representative of the family Himerometridae that has been found in America. 



From the same material he also segregated fragments that he referred to Micro- 

 crinus cf. conoideus Ernmons and to Glenotremites (Paleantedon) carolinianus, sp. 

 nov. 



TYPES OF ARM BRANCHING IN THE COMATULIDS 



Dr. Gislen has divided the arm branching in the comatulids into 85 types, which 

 are (omitting those found only in fossil forms) as follows: 



(2) Eudiocrinus type (Eudiocrinus only). (3) Pentametrocrinus type (Pentametro- 

 crinus and Atopocrinus) . (4) Thaumatocrinus type (same as the preceding, but with 

 10 radials). (7) Comatula pectinata type (10-armed species of Comatula, and Coma- 

 tulella). (8) Zygometra pristina type (Zygometra pristina and 10-armed young of 

 Zygometra and Catoptometra) . (9) Antedon type (the majority of comatulids). (10) 

 Monachometra fragilis type I. (11) Promachocrinus type (Promachocrinus only). 

 (15) Comatula rotcdaria type (Comatula rotalaria only). (16) Comatella maculata 

 type. (17) Neocomatella pulchella type I. (18) Neocomatella alata type. (19) 

 Comatella brachycirra type. (20) Asterometra type. (21) Stenometra diadema type. 

 (22) Monachometra jragilis type II. (23) Diodontometra type. (25) Catoptometra 

 rubroflava type. (26) Catoptometra hartlaubi type I. (27) Perissometra macilenta 

 type. (28) Pachylometra angusticalyx type. (29) Heterometra bengalensis type. (30) 

 Comanthus solaster type. (31) Adelometra angustiradia type. (32) Crinometra imbri- 

 cata type. (32a) The abnormal Comanthoides spanoschistum type. (33) Capillaster 

 coccodistoma type. (34) Nemaster discoidea type. (35) Heterometra compta type. 

 (37) Comatella stelligera type. (38) Catoptometra magnifica minor type. (39) Neo- 

 comatella pulchella type II. (40) Crinomeira concinna type. (41) Stylometra spinifera 

 type. (42) Stephanometra spicata type. (43) Mariametra subcarinata type. (44) 

 Comanthus parvicirra type I. (45) Comaster serrata type. (46) Crossometra sep- 

 tentrionalis type. (47) Zygometra comata type. (48) Heterometra crenulata type. 

 (49) Cornantheria rotula type. (50) Oceanometra magna type. (51) Comanthus 

 japonica type. (52) Comanthus timorensis type I. (53) Himerometra martensi type. 

 (54) Crinometra transversa type. (55) Catoptometra hartlaubi type II. (56) Coman- 

 thus parvicirra type II. (57) Comanthus timorensis type II. (58) Crinometra in- 

 sculpta type. (59) Heterometra nematodon type. (60) The irregular Comanthus 

 timorensis type III. (61) Nemaster grandis type. (62) Capillaster multiradiata 

 type. (63) Capillaster macrobrachius type. (64) Capillaster mariae type. (65) 

 Comaster gracilis type I. (66) Comatella nigra type. (67) Catoptometra magnifica 

 type. (68) Oxymetra erinacea type. (69) Pontiometra andersoni type. (70) Coman- 



