OXFORD UNIVERSITY SPIISBERGEN EXPEDITIOX. 1111 



It was tlius to be expected tliat Enchytrgeids should constitute 

 tlie bulk of the collection. There is no naention of snow in the 

 data relating to the worms ; and since they thus jDass at least a 

 part of their life on or in ground free from snow, the conditions 

 undei' which they live a,re those of Welch's Enchytrceus gelidus 

 i-ather than of M. solifugus var. i-ainierensis. 



ZOOGEOGRAPHICAL ReLATIOKS. 



The Oligochfeta may be divided, with reference to their habitat, 

 into limnic, littoral, and terrestrial forms; and the Oligochseta 

 of Bear Island and Sipitsbergen may be classified under these 

 lieadings as follows :— 



Limnic. Littoral. Teeeesteial. 



N'aisJosincB. Lumhincilhis necrojyliagus. Henlea brucei. 



Henlea Jieleotrophus. Lumhricillus cegialites. JSnchytrcBus allidus. 



Henlea spp. (2). Ltmihricillus fossarum. Fridericia leydigi. 



JSnchy trails cri/modes. Ijiimhrioillus lienkingi. Ilesencliytrceiis sp. 



EnchytrcBus sp. Ziwnhricillus pagenstecJieri. 



MesencliptrcBus sp. Marionina eoudensis. 



JSnchgtraus albidu.t. 

 JSncltgtrceus cri/modes. 



There is no I'ecord of the habitat of some of the previously 

 recorded species : of Lumhricillus fossarimi, which, however, is 

 elsewhere found on the shore, and is therefore so entered here ; 

 of E nchytrceus albidus recorded from Bear Island by Ude, which 

 is also entered as littoral, since all his specimens from Bear Island 

 of which the habitat is recorded were littoral, and the worm is 

 elsewhere common on the shore ; and of Fridericia leydigi, which 

 is entered as terrestrial, since most of the Fridericias are so. 



All the smaller Oligochseta, and therefore all the forms which 

 are represented in the present and former collections from Spits- 

 bergen and Bear Island, are easily transported, and hence are of 

 •only slight value for considerations of zoogeogra,phy. Limnic 

 forms have a great diversity of means of dispersal ; they may 

 spread directly throughout a river system — though this, cf course, 

 has no bearing on the present enquiry; their cocoons are easily 

 transported in the mud which adheres to the feet of wadin"' 

 birds ; some forms are known to encyst, and hence may be trans- 

 ])orted by birds even in the adult state. As a consequence of 

 this easy distribution, the same genera — sometimes even the 

 same species — are found in widely distant places; the case is 

 similax to that of the Rotifera and Protozoa, of which the same 

 genera and species are found in ponds and streams all over the 

 woi'ld. To illustrate by means of an example, there appears to 

 be but one genus, Branchiodrilus, of limnic Oligochosta which is 

 peculiar to India, while a number of species are found both in 

 India and England, or India and Europe (species of ]'y'ais, Chccto- 

 _gast.er, Dero, Aulophortcs, F^'istina^, etc.). 



74* 



