Page:The Zoologist, 4th series, vol 1 (1897).djvu/485

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 segments. The tubercula are also more variable, being (1) absent, (2) on alternate segments, or (3) on a variable number of segments, either as papillæ or in the form of a band on the ventral surface of the clitellum. The male pores are on segment 15, and with or without papillæ. There are eight setæ on each segment, sometimes 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, Sav.=longa, Ude. 28–35/32–34. 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 investigated.

7. A. profuga, Rosa. 30–35/31–34. 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. 28–34/31:33. 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. Ribaucourt has gone carefully into the whole matter.

9. A. trapezoides, Dugès. 27–34/31–33. Note that in one case the papillæ 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 hybridity—a subject which I have discussed in 'The Naturalist' (October, 1892).