430 



PROF. F. J. BELL ON THE TEMNOPLEURID.«. [June 1, 



enormous abactinal system, its comparatively large anal area, and 

 its small rounded actinostome with a thin complete edge. 



The following measurements of the specimens from Bondy Head 

 and "Portugal" may be compared with those given by much 

 younger and by intermediate specimens. 



It is obvious from the above figures that the most marked changes 

 occur in the actinostome, which, almost large in the young, becomes 

 so small in the well grown forms ; and it is interesting to compare 

 the change with what obtains in TemnopJeurus. T. toreutnaticus 

 has the actinostome even proportionally larger when young ; but its 

 adult specimens (50 niiUims. in diameter) present a percentage value 

 for their actinostome of as much as 20, the relation between the 

 young Salmacis and the adult Temnopleunis being, even in the 

 character of the actinostome, not obscurely indicated. 



The following points may also be noted in the young specimens: — 

 The lozenge-shaped patches are not yet apparent ; the sutural pores 

 are much more distinctly marked ; there is only one distinct series 

 of primary tubercles in each set of coronal plates above the ambitus ; 

 below the ambitus there are indications of a second and, still more 

 faintly, of a third series in the interambulacral areae ; the anal covering- 

 plates are for the most part large, and consequently few in number ; 

 the most striking in the specimen, 22'5 millims. in diameter, are five 

 peripherally placed plates, which are separated from one another by 

 small triangular plates, one for each. 



The test is much thinner in the fully grown than in the young 

 specimens ; the bare median spaces are more considerable in this 

 than in any other species of the genus ; and the tubercles are pro- 

 portionally smaller ; the actinal surface becomes a little swollen, so 

 that the actinostome becomes somewhat depressed ; the ridges con- 

 necting the not strongly developed auricles are low ; the madreporic 

 is hardly larger than the other genital plates ; the anal opening is 

 at or close to the centre of the anal area. 



4. Salmacis sulcata, Ag. 



Salmacis sulcata, Agassiz & Desor, Catal. Rais., Ann. So. Nat. 

 (3) vi. p. 359. 



Test rounded, or somewhat conical, closely covered with spines 

 of a general green coloration, but becoming almost white towards 



