MONOGRAPH OF THE EXISTING CRINOIDS. 

 Zenometra columnaris. 



h'. The plates are very narrow and baud-like. 



Psathyrometra borealis. Thatimatocrinus bureaUs. 



Psathyrometra fragiUs. Isometra vivipara. 

 <?. Each lappet contains a single rod or spicule. 

 (?. The rods or spicules are straight. 



Comatonia cristata. Tropiometra picta. 



Himerometra martensi. Tropiometra indica. 



Mariametra delicatissima. Antedon petasus. 



Cullometra disciformis. Compsometra loveni. 



Cyllometra albopurpurea. Compsometra incommoda. 



Decametra taprolanes. Erythrometra ruber. 



Decametra tigrina. Erythrometra austraUs. 



Decametra parva. Heliometra maxima. 



Cololtometra vepretum. Heliometra glacialis. 



Colobometra discolor. Florometra marte. 



Prometra chadwicki. Florometra. asperrima. 



Cotylometra gracilicirrn. Florometra serrati-ssima. 



Oligometridcs adeonce. Florometra magellanica. 



Oligomctra carpenteri. Psathyrometra gracillima. 



Oligometra serripinna. 



e*. The rods or spicules are curved or bent. 



f. The convexity of the curve Is outward and proximal. 



Oatoptometra hartlauU. Coccometra hagenii. 



Catoptometra ophiura. Tfanometra clymene. 



Amphimetra papuensis. Florometra marice. 



Oxymetra fiinschii. Florometra laodice. 



Cyllometra albopurpurea. Florometra asperrima. 



Prometra chadioicki. Florometra serratissima. 



Antedon petasus. Cyclometra clio. 



Compsometra loveni. Trichomctra cubensis. 



Toxometra paupera. Thaumntocriivus borealis. 



Jridometra adrestine. Pentametrocrinus tuberculatus. 



Iridometra melpomene. Pentametrocrinus japonicns. 



Andrometra psyche. Pentametrocrinus variuns. 

 Coccometra nigrolineata. 



f. The convexity of the curve is Inward and distal. 



Comntonia cristata. Psathyrometra antarctica. 



Dichrometra doderleini. HatJirometra prolixa. 



Mariametra delicatifsima. Uathrometra tenella. 



Decametra mylitta. Hathrometra sarsii. 



Olignmetra scrripinna. Thaumatometra tennis. 

 Hypalnmetra dcfcctn. 



From the preceding analysis it is evident that the relationships between the 

 various types of adambulacral structures and the systematic position of the. species 

 is quite similar to the relationships between the latter and the various types of 

 cirri; that is to say, only a small minority of the systematic units have character- 

 istic adambulacral plates. It is interesting to note further that the systematic 



