iSs 



BRITISH ANNELIDS. 



WITH ESPECIAL REFERENCE TO THE EARTHWORMS OF ESSEX. 



By REV. HILDERIC FRIEND, F.L.S. 

 (Continued from page 1^4.) 



A LTHOUGH Eisen discovered an example of a worm which lived 

 "^^ among decaying timber upwards of twenty years ago, and named 

 it the "Tree-haunter" {Dendrobana), yet the species or group was 

 never studied in a consecutive and exhaustive manner, either at 

 home or abroad, until I took it up two years ago, and published my 

 results in the "Journal of the Linnean Society" for 1892 {Zoology, 

 vol. xxiv., pp. 292 seq.). Since that sketch was written, I have been 

 able to extend my researches and add more than one fact of very 

 great biological interest and importance to those already known. My 

 present paper will be limited to a notice of this third group of worms 

 belonging to the genus AUolobophora. 



Allolobophora : §3, Dendrob^na. 

 The worms belonging to this group are of two kinds. They can 

 (with some exceptions, perhaps) live either in the soil or in the 

 timber of decaying trees. Their habitat materially affects their size, 

 colour, shape, and appearance. So much is this the case that it is 

 in some instances almost impossible to decide whether the terrestrial 

 species is the same as the dendrobcenic or not. This is a point of 

 extreme interest, as we have here a means of studying, in careful 

 detail, the effect of environment on species, and the possible ultimate 

 development of species from varieties. The varieties which frequent 

 trees are invariably of a warm brown colour on the back, with the 

 girdle and under surface lighter. They seldom exceed one and a-half 

 inches in length, and have an octangular-shaped tail, due to the wide 

 disposition of the setae, which are in eight almost equidistant rows. 

 The prostomium may not cut the peristomium at all, or it may perfectly 

 bisect it. The girdle occupies from five to eight segments, com- 

 mencing somewhere between the 24th and 31st. The male or 

 spermiducal pores are on segment 15, usually with prominent 

 papillce, which in one case extend over the two adjoining segments. 

 The clitellar papillae {tubercula pubertatis) are either absent, or occur 

 on two or three consecutive, never on alternate, segments. The first 

 dorsal pore is usually bet\ueen the 5th and 6th segments. I have 

 found spermatophores only on the terrestrial forms of two species. 



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