A MONOGRAPH OF THE EXISTING CRINOIDS 41 



found. A number of points in the ecology and distribution of the recent crinoids and 

 Uintacrinus were discussed. It is suggested that side and covering plates may have 

 arisen through the detachment of produced ventrolateral margins of the brachials 

 and pinnulars. The origin of the Mediterranean and Atlantic crinoid faunas from 

 that of the Indo-Pacific region is explained. 



The genus Comanthus is divided into three subgenera, as follows: 



Comantheria (genotype Antedon briareus Bell). 



Comanthina (genotype Actinometra nobilis P. H. Carpenter). 



Comanthus, s. s. (genotype Comanthus intricata A. H. Clark = Actinometra valida 

 P. H. Carpenter). 



The subgenus Comanthus as restricted includes two incompletely differentiated 

 groups to which the following new names are applied: 



Bennettia (genotype Alecto bennetti J. Miiller, 1841). 



Validia (genotype Comatula rotalaria Lamarck, 1816). 



The following names are included in the synonymy of Comanthus (Comanthus) 

 rotalaria (Lamarck): rotalaria, parvicirra, timorensis, wahlbergii, brevicirra, trachy- 

 gaster, intricata, mertensi, armata, polymorpha, simplex, meyeri, mutabilis, annotea, 

 elongata, simfjlex (2), quadrata, guttata, orientalis, and helianthus. 



The variation in the length of the anterior arms in Comatula pectinata and their 

 occasional extreme attenuation are described, and specimens of that species with 

 more than 10 arms are recorded. 



The new family Colobometridae is created to include the genera Oligometra, 

 Cyllometra, Colobometra, and Cenometra. 



The new species included are : 



Amphimetra Jormosa. Colobometra vepretum. 



Heterometra aspera. Stenometra dorsata. 



Amphimetra Jormosa is not described; the first reference shows that the species 

 is based upon a specimen dredged at Albatross station 5138, Philippine Islands, and at 

 first considered conspecific with A. discoidea from Queensland; a detailed description 

 was drawn up for publication in volume 36 of the Proceedings of the United States 

 National Museum, and it was assumed that this description would appear before the 

 report upon the Copenhagen collections, but it was later withdrawn. A specimen 

 was recorded hi the Copenhagen collection from Singapore and its essential characters 

 given; the characters distinguishing this form from A. discoidea are also given. 



Stenometra dorsata is not described, but the characters of two of the specimens 

 are given. It is the Japanese species previously recorded as (Stenometra) quinque- 

 costata of P. H. Carpenter. 



A list of the 24 species of comatulids collected in shallow water at Singapore by 

 Mr. Svend Gad is appended; 2 additional species known from Singapore are cited; 

 and 13 additional genera, undoubtedly including shallow water species in the same 

 region, are given. 



In a paper published in January, 1910, the origin of the muscular articulations 

 of the crinoids was discussed; the muscle pairs in the crinoids were assumed to be 



