120 Proceedings of the Royal Irish Academy. 



continental species, is the Lumbricidfe or earth-worms proper ; and even here 

 our knowledge of the Scotch and Welsh species is very inadequate. 



The numbers in brackets refer to the Bibliography at the end of the 

 paper. 



Distribution. 



1. Ecological. 



The mouutams in the British Isles are scarcely high enough to have a 

 pronounced alpine fauna ; and I have unfortunately not been able to obtain 

 specimens from a greater height than 2000 feet. The most characteristic 

 OligoohcCte at this elevation is the small Enchytrteid Marionina spJiagiutorum 

 (Vejd.), which almost invariably occurs in the soil and peat on mountains 

 and elevated moors. I have found it on theEeeksin Kerry (1500 ft.) ; Lough 

 Salt Mountain, Co. Donegal (1500 ft.) ; Callary Bog, Co. Wicklow (1000 ft.) ; 

 Snaefell summit. Isle of Man (2000 ft.); and various other places. Its 

 continental distribution also seems to indicate that it is an alpine form. 



Aclueta hohemica (Vejd.) was also found on the summits of Snaefell and 

 Lough Salt Mountain ; but it also occurs near sea-level on the cliffs at Port 

 Erin, Isle of Man. 



The following species have been taken at elevations between 1000 

 and 2000 ft., though they are also common at sea-level. 



Lumbricus ruhellus. Helodrilits chloritica. 



Helodrilus Eiseni. Eiseniella tetraedra, typ. (in lake 

 Helodnlus constridus. 1500 feet high in Kerry). 



H. rvhichis. 



A number of species are generally to be found under the bark of fallen 

 trees. The earth-worms most frequently found in this habitat are — Eisenia 

 rosea, Helodrilus rvMdus, H. mamraalis, Lumlrncus ruhellus, Z. castaneus, and 

 Z. festivus. The cocoons of these worms are common in the loose material 

 between the bark and the wood. This habitat is also favoured by numerous 

 Enchytrseids, including Fridericia Bretscheri, F. striata, Bryodrilus Ehlersi, 

 &c. The only sharp ecological di^dsion of the aquatic Oligochasta is between 

 the marine and the fresh-water species. The marine forms are found 

 commonly between tide-marks under stones, among weeds, in the sand, &c. 

 Characteristic species are — Enchytrcpus alhidus, Ltcnihricillus litoreus, Z. verru- 

 cosus, Z. fossarum, Z. Evansi, Marionina sernifusca, Clitellio arenarius, Tv.bifex 

 Benedeni, T. costatus, &c. 



Only a few species are to be found in the rapid mountain streams. They 

 belong to the families ^olosomatidte and Naididse. The most characteristic 



