128 TANAIS. 



of short triarticulated filaments, resembling the superior 

 antennae in structure, and possibly performing similar 

 functions. 



We have received specimens of this species from Ber- 

 wick Bay, captured by our late friend Dr. George 

 Johnston, also from Mr. David Robertson, of Glasgow ; 

 as well as a considerable number of individuals captured 

 by Mr. Loughrin, at Polperro, who informs us that they 

 live gregariously below high-water mark, where they 

 protect their small colony by retiring deeply within the 

 fissures of the slaty rocks of the coast, where they collect 

 together a mass of material of a " leathery consistence," 

 behind or within which they take shelter. When dis- 

 turbed they escape, and will spring to a considerable 

 distance. This is probably done by bringing the head 

 and tail together and suddenly straightening themselves. 



Among the several specimens sent to us by Mr. Ro- 

 bertson, was one of a very slender form ; so peculiar 

 was it that we figured it under the impression that it was 

 of a separate species from the present, and named it in 

 the dredging list as T. Mrticaudatus.* But among the 

 hundreds that we have had the opportunity of examining 

 from several localities, we could identify many that 

 were intermediate between the two extremes, and con- 

 sider it not improbable that the slender form is but a 

 specimen that had recently cast its skin. 



* Brit. Assoc. Rep. 1860, p. 225. 



