1112 BR. J. STEPHENSOX ON THE OLTGOCHiETA OF THE 



Littoral forms, living on the shore and exposed at times to 

 immersion in salt water, have additional means of dispersal. Being, 

 unlike Oligochaetes in general, immune to salt water, they can be 

 transported in masses of seaweed ; or more commonly their 

 cocoons are so transported, entangled in masses of weed or other 

 detritus. Not only can they take possession of a whole coast, and 

 spread along the shore-line, but they may in this way travel over 

 sea for long distances. Pontodrilus, for example, which occurs 

 along the coasts of India, has a circummundane distribution. 



Even terrestrial Oligochaeta are by no means always dependent 

 on their own unaided activities for enlarging their distribution; 

 there are a considerable number Avhich are especially liable to be 

 transported accidentally — by man or other agencies, — and which 

 show an especial capacity for establishing themselves where they 

 happen to be deposited. The smaller the worms the easier is 

 their dispersal; certain small species of earthworms of the genus 

 Dichoyaster^ which has its proper home in A.frica, have s[)read all 

 round the w\armer regions of the g-lobe. 



few, however, possibly none, of the worms of Spitsbergen and 

 Bear Island are exclusively terrestrial. Of those given as 

 terrestrial in the above table, Enchytrceus cdbidus is often found 

 on the shore; it is perhaps the most widely distributed of all 

 Enchytneids, and occurs all over Europe, in North America, and 

 in South America as far as Patagonia and Tien a del Fuego, as 

 well as within the Arctic circle iu Greenland and Nova Zernbla 

 The species of Mesenchytrceus found at Cape Boheman among 

 plants in dry tundra was also obtained among mosses on the 

 banks of a freshw-ater pond, more or less under water, and is 

 therefore limnic as well as terrestrial. The Henlea found a.mong 

 Dryas etc. on a hill near the coast of Freshwater Bay was also 

 found in the Bruce City region, possibly in a limnic or littoral 

 hahitat (details of habitat are wanting for this tube). Fridericia 

 leydigi, previously obtained from Spitsbergen, is probably the 

 most strictly terrestrial of all the above species, occurring else- 

 Avhere in earth rich in humus and under moss. 



There can thus be no question of anything peculiar in the 

 Oligochsite fauna of Spitsbergen and Bear Island. All the 

 geneva are ensily transported, and all (except perhaps the Naidid 

 genus Xais) have previously been found within the Arctic circle 

 — Henlea in Nova Zembla, N. Siberia, N. Bussi;t, N. Norway, 

 and in the Canadian Arctic; Enchytrceus in N. Russia. Green - 

 la,nd, and the Canadia,n Arctic; Ztcmbricillus in Nova Zembla, 

 N. Siberia, the Canadian Arctic, and Greenland ; Fridericia in 

 Nova Zembla, N. Russia, and N. Siberia. All these genera also 

 occur in Alaska. 



As to wdiether particular species of Spitsbergen Oligochseta 

 have been evolved locall}^ or imported, it is as yet impossible to 

 say, uiatil neighbouring lands have been more thoroughly 

 explored. There is some slight ground for supposing that some, 

 at least, mny have been evolved on the island. On the whole, no 



