MONOGKAPH OF THE EXISTING CKINOIDS. 293 



Oaloptomctra Jiartlaubi. Colobometra vepretum. 



Heterometra qiiinduplicava. Colobometra discolor. 



AmpJiimetra parilis. Cotylometra gracilicirra. 



Dichrometra ciliata. OligomctrirJcs adeoim. 



Cenometra lierdmani. Compsometra incommoda. 



Decametra taprobanes. Hypalometra defecta. 



Decametra mylitta. Promachocrinus Jcerguelcnsis. 



Decametra parva. Thaumatometra tennis. 



d'. Two bands of spicules, a proximal and a distal, which finally meet and unite. 



Leptonemaster venustiis. Heterometra bengalensis. 



Comatonia cristata. Heterometra compta. 



Eudiocrinus junceus. Heterometra reynaudii. 



Eudiocrinus pinnatus. Heterometra quinduplicava. 



Eudiocrinus venustulus. Stephanometra echinus. 



Himerometra bartschi. Oxymetra aranea. 



Craspedometra acuticirra. Lamprometra protectus. 



Heterometra savignii. Oligometra serripinna. 

 Heterometra philiberti. 



6 2 . Tip of the tentacles protected by a calcareous cap, button, ring, or rudimentary plate. 



Neometra alecto. Gephyrometra propinqwa. 



Neometra acanthaster. Pectinometra carduum. 



'Neometra conaminis. Pectinometra flavopwpurcn. 



Neometra gorgonia. Calyptometra lateralis. 



Calometra caJlista. roecilometra scalarix. 

 Calometra discoidea. 



A detailed examination of the tentacles was made in 172 individuals. 



Usually all the tentacles in a given specimen agree more or less closely in 

 the frequency and character of their deposits, but this is by no means always the 

 case; it frequently happens that deposits, commonly a few spictiles, occasionally 

 considerable aggregations, are found in one or two tentacles of a pinnule but are 

 entirely absent in the remainder, while in the Charitometridre the tentacles in 

 which the tip is protected by a more or less developed plate are mostly confined 

 to the base of the pinnules. 



When adambulacral deposits are absent, deposits in the tentacles are usually 

 also absent, but this is not always so, for in several species in which there is no 

 trace of adambulacral deposits the spiculation of the tentacles is very highly 

 developed. Though in the Caloinetridse, Thalassometridse, and Charitometridae 

 the adambulacral deposits are very highly developed, for the most part spicules 

 are few or quite lacking in the tentacles. 



In many cases the spicules in the tentacles are far more conspicuous than 

 the adambulacral deposits, which are often difficult to distinguish from the usually 

 enlarged basal spicules of the tentacles. 



Of the 172 individuals 87, or approximately half, distributed in all the groups 

 represented, were found to be without deposits in the tentacles; 28, representing 

 the Comasteridae, ZygometridEe, Himerometridse, Mariametridse, and Colobo- 

 metridse, with a few Antedonidse, showed numerous spicules in a conspicuous band 

 along the outer side; 23, representing all groups excepting the Stephanometridse 



