566 



PEDICELLINID^. 



Fig. 36. 



The form of the body is liable to some variation, apart 

 from the changes which are due to the different degrees 

 of contraction. It is occasionally much elongated (Plate 

 LXXXI. fig. 2) ; but commonly it is rather short,, very 

 gibbous on one side, and almost straight 

 on the other. In one marked variety 

 the peduncle is quite destitute of spines ; 

 but normally they are present in great 

 numbers, and sometimes are also scat- 

 tered sparsely over the body *. 



The movements of the peduncle are 

 vigorous and lively : the polypides, when 

 excited, dash themselves vehemently from 

 side to side ; and one striking against 

 another, the commotion spreads through- 

 out the colony until " the effect is that of 

 a field of corn swept by a strong breeze " f. 



The body, which is separated from the 

 stem by a distinct diaphragm, is deci- 

 duous ; it falls, and after a time is re- 

 newed by a process of gemmation, the 

 headless stalk retaining its muscular ac- 

 tivity. 



The larvae, according to Joliet, are pro- 

 duced throughout the summer, from May p^ai,,^^^ ,,„,„„. 

 to September, but especially in May and 

 June. 



It is with extreme reluctance that I have abandoned 

 Sars's familiar name for this species ; but, according to 

 the ordinary laws of nomenclature, there can be no doubt 



* Joliet states that he has often found amongst a group of polypides 

 with smooth peduncles an individual furnished with spines, and that in 

 some eases these appendages ocfur only on a section of the length of the 

 .item or on one of its sides. 



t Van Beneden. 



