MONOGRAPH OF THE EXISTING CKINOIDS. 641 



In 1884 Bell greatly extended the known range of Ophiomasa caeaotica, record- 

 ing it from Suez and from Queensland. 



In 1888 Brock described as commensals on comatulids Ophiomasa cataphracta 

 from Cape York, and Ophiocethiops unicolor and Ophiosphwra insignis from Am- 

 boina. In 1895 Professor Koehler described Ophiocethiops elegans, and in 1898 

 Ophiomasa mcerens. In the latter year Prof. Ludwig Doderlein described Ophio- 

 phthirius actinometrce. 



In 1904 Kcehler redescribed and revised Brock's species, but without discussing 

 their commensalism. 



In 1908 H. C. Chadwick mentioned ophiurans, possibly Ophiomasa caeaotica, 

 but more likely a species of Ophiactis, on comatulids in the Red Sea ; and in 1915 

 Lieut. F. A. Potts published the results of his studies on the commensals living 

 on comatulids in Torres Strait, listing Ophiocoma, sp., Ophiactis, sp. (later described 

 by Dr. H. L. Clark as 0. delicata), Ophiomasa caeaotica, 0. caeaotica var. picta, 

 and 0. obscura. 



Family TRICHASTERID^]. 



The species of this family live upon arborescent marine organisms, and many 

 of them are quite active in their movements. Such of the species as live within 

 the range of the pentacrinites are undoubtedly occasionally to be found upon them. 



Family GORGONOCEPHALID^E. 



Most, if not all, of the species of this family with undivided, or infrequently 

 divided, arms, and many of those with ramose arms, as A sir ocy nodus and Astro- 

 caneum, normally live attached to arborescent organisms. Such species as occur in 

 the regions inhabited by the pentacrinites may be expected occasionally to be found 

 upon them. 



ASTROGOMPHUS VALLATUS LYMAN. 



This species is not uncommon on specimens of Isocrinus decorus taken off the 

 northern coast of Cuba. 



ASTEROPORPA ANNULATA LUTKEN. 



In 1873 Wyville Thomson figured a specimen of Isocrinus asteria to the cirri 

 of which was clinging an individual of this species. 



Family HEMIEURYALID^. 



The remarks under the preceding family heading apply equally to the species 

 of this family. Sigsbeia murrhina Lyman has been found upon the species of 

 Isocrinus in the Caribbean Sea. The similarity in the type of coloration between 

 Sigsbeia lineata Liitken and Mortensen and the echinoderms and crustaceans nor- 

 mally commensal on crinoids is striking. 



