MONOGRAPH OF THE EXISTING CKINOXDS. 



291. 



(1) The basals and orals in the early larva are perisomic plates, not having as yet 

 assumed tlieir ultimate status of primary plates; (2) the plates of the crinoid 

 calyx originated as a development from an integument filled with minute spicules; 

 and (3) the spicules in such an integument may develop individually into special- 

 ized forms, such as large spicules, rods, scale-like plates, buttons, or anchors, or 

 through plates of the perisomic type into the typical crinoid plates. 



There is an interesting superficial similarity between the side and covering 

 plates in the crinoids and the so-called "snowshoes" developed (from modified 

 feathers) along the sides of the toes of certain grouse in winter (fig. 762, p. 353) to 

 increase the area covered by the feet, and thus to enable them to travel over 

 soft snow. 



TENTACLKS. 



In the details of their anatomical and histological structure the tentacles 

 appear to vary but little in the ditferent groups. There is great diversity, however, 

 in the extent to which calcareous deposits are developed within them. 



These calcareous deposits, when present, are always in the form of small 

 spicules, sometimes smooth, straight, or bent, but usualW roughened or studded 

 with minute spines and more or less irregular. 



The manner of occurrence of these spicides is indicated in the following table : 

 a}. No ciilcareous deposits ia the tentacles: 



Comatella nigra. 

 Comaiella stelUgera. 

 Comatella maculata. 

 CapiUaster sentosa. 

 Capillaster multiradiata. 

 CapiUaster coccodistoma. 

 Comissia Uttoralis. 

 Comatula pectinata. 

 Coniaciinia meridionalis. 

 ComatuHdes australis. 

 Comaxter minimns. 

 Comantheria polycncmU. 

 Covmnthua pinfitiis. 

 Comanthus siilaster. 

 Comanlhus japonica. 

 Comanthus trichoptera. 

 Comanthus annulata. 

 Zygometra microdiscus. 

 Zygometra elrgans. 

 Catoptometra magniflca. 

 Bimcrometra martensi. 

 Himerotnetra magnipinna. 

 Himerometra rohustipinna. 

 Heteromctra crenulata. 

 Heteromctra pulchra. 

 JInmalometra dcnticulata. 

 Amphimetra spcctahUis. 

 Amphimetra ducoidea. 



Amphimetra papuensis. 

 Stephanometra monacantha. 

 Fontiometra andersoni. 

 Oxymetra flnschii. 

 Dichrometra fiagellata. 

 Dichrometra dodcrlcini. 

 Mariametia subcarinata. 

 Mariametra dclicatissima. 

 Lampromctra palmata. 

 Ccnometra delicata. 

 Cenometra unicornis. 

 Cyllometra albopurpurea. 

 Decametra parra. 

 Priimetra rhaduirki. 

 OUgometra carpenteri. 

 Cosmiometra orassidrra. 

 Tropiometra macrodiscus. 

 Tropiometra afra. 

 Tropiometra carinatn. 

 Tropiometra picta. 

 Tropiometra indica. 

 Antedon petasvs. 

 Anted<m bifida. 

 Antedon adriatica. 

 Toxometra paupcra. 

 Eumetra chambcrlaini. 

 Irid^metra adrestine. 

 Iridometra nielpomene. 



