EABTHWOBM STUDIES. 457 



ment of a true Lumbricus. There is a greater range in the number 

 of girdle-segments than is found in the former genus. While in 

 the British Lumbrici they number six, with the single exception 

 of L. papillosus, in this genus they cover from four to ten seg- 

 ments. The tubercula are also more variable, being (1) absent, 

 (2) on alternate segments, or (3) on a variable number of seg- 

 ments, either as papillae or in the form of a band on the ventral sur- 

 face of the clitellum. The male pores are on segment 15, and with 

 or without papillae. There are eight setae on each segment, some- 

 times geminate as in Lumbricus, at other times more or less 

 irregularly disposed. They are usually cylindrical throughout, 

 and frequently exude a turbid fluid which is sometimes very 

 pungent. The colour range is not limited as in Lumbricus. It 

 varies from blue (in A. profuga) to green, ruddy brown, flesh, clay- 

 colour, and alternate bands as in the Brandling. This is by far 

 the largest genus, and has almost a world-wide distribution. The 

 species, subspecies, and varieties known to science now number 

 nearly one hundred. The following are known in the British 

 Isles : — 



6. Allolobophora terrestris, Sdiv. — longa, Ude. ^E^i* Very 

 widely distributed, and often confused with L. herculeus, though 

 easily distinguished therefrom. A pale variety (lactea) often 

 found. The causes of variation have not yet been fully in- 

 vestigated, 



7. A. profuga, Rosa. ^E^- Well-marked species; usually 

 steel-blue, with yellow tail and light-coloured girdle. Found in 

 Ireland, North Wales, and several English counties. 



8. A. turgida, Eisen. g^r^' Widely distributed, and formerly 

 confused with the next, with which also Mr. Beddard wrongly 

 associates it under the name calignosa. I admit that turgida and 

 calignosa are the same, but trapezoides is quite distinct. Ribau- 

 court has gone carefully into the whole matter. 



9. A. trapezoides, Duges. f^Eff. Note that in one case the 

 papillae are on two alternate segments (31 : 33), while in the 

 other they cover three consecutive segments (31 — 33). There 

 are other differences which at once appear when a good series 

 is under examination. Beddard's remark that Michaelsen found 

 an intermediate form seems to me to suggest the question of 

 hvbridity — a subject which I have discussed in ' The Naturalist' 

 (October, 1892). 



