90 



Table of the species of Pleureehinus. 



1. Only five buccal plates and tube feet; anal opening cen- 

 tral, no anal plate. Spines thorny. Globiferous pedicel- 



lariæ with a large unpaired lateral tooth PL Döderleini Mrtsn. 



Ten buccal plates and tentacles. A more or less 

 distinct anal plate. Spines smooth or thorny. Globi- 

 ferous pedicellariæ with 1 — 1 lateral teeth or with only 

 a rounded knob on one or either side below the end- 

 tooth 2. 



2. Pits small; spines smooth. Globiferous pedicellariæ with- 

 out lateral teeth, the blade very short 3. 



Pits large, reaching to the base of the primary tubercles. 

 Globiferous pedicellariæ without teeth or with 1 — 1 lateral 

 teeth; the blade not very short 4. 



3. Pores rather large; ambulacral plates lower than the 

 interanibulacral ones, their number being somewhat larger. 

 Colour of test red; the spines red with white bands. Ge- 

 nital plates without transverse line PI. ruber Döderl. 



Pores very small; ambulacral plates as high as the 

 interambulacral ones, their number being the same. 

 Colour oftest gray; the spines reddish at the base, mostly 

 with a small dark band in the outer part. The outer 

 part of the genital plates separated from the inner part 

 by a sinuous line PI. variegatus Mrtsn. 



4. Globiferous pedicellariæ with 1 — 1 distinct lateral teeth; 

 spines smooth, with intensely red bands. Test uniformly 



dark coloured PI- bothryoides Agass. 



Globiferous pedicellariæ without lateral teeth, only a 

 rounded knob on one or both sides below the endtooth 5. 



5. Spines thorny, at least the secondary ones, not swollen 



at the point PI scillœ (Maz.). 



Spines smooth, the primary ones swollen at the point. (î. 



6. The genital plates divided by a transverse line into an 

 outer and inner part; the secondary tubercles arranged in 



a horizontal row PI- maculatiis Mrtsn. 



The genital plates not divided into two parts by a 

 transverse line; the secondary tubercles not forming hori- 

 zontal series PI- sianiensis Mrtsn. 



