56 



The Irish Naturalist. 



May, 



differences are very marked. The majority are large 

 somewhat irregular " scale-spines," but there are also 

 small conical tooth-shaped spines or " denticles." 



2 r * » 



e » 0 



I mm. ^ 



Fig. 4. Comparison of spines on the corresponding areas of another 

 specimen of the same. x 20. 



The comparison of the latero-ventral areas on the right 

 and left sides of a single specimen show variations quite 

 as considerable as those in different specimens. In one case 

 (fig 3.) the eighth area on the right side have no real spines, 

 whereas on the left they are four in number, two scale- 

 spines and two denticles, all small though well developed. 

 Similarly on the sixth latero-ventral area the right side has 

 one large scale-spine as against six medium-sized spines 

 on the left. 



Similar numerical variations were found on all the 

 segments of this and other specimens (see fig. 4.) ; in some 

 segments the right side bearing a preponderence of spines, 



