The Earthworms of Ireland. 289 



SPECIFIC CHARACTERS. 



I.— Allurus tetraedrus, vSavigny— A small worm, seldom reach- 

 ing two inches in len<,4h, usually about one to one and a-half inches 

 when crawling about, but able to stretch to two or even three inches in 

 the case of the largest specimens. Body somewhat cylindrical before 

 four-angled behind the girdle, which is prominent, and closely fused' 

 It often appears to encircle the whole body, is lighter in colour, an(i 

 normally extends from the 22nd to the 27th segment. A glandular 

 ridge connects the girdle with the male pores on the 13th segment 

 These latter pores are well seen, being seated on somewhat conspicuous 

 papillae. The oviducal pores are on segment 14, thus being behind the 

 male pores, while in Lumbriais they are in front. Dorsal pores com- 

 mence between the 4th and 5th segments. In addition to the ordinary 

 setae, situated at the angles of the body, there are rod-shaped bristles on 

 the segments which contain the essential organs, as well as minute claw- 

 like setae or spines scattered over the body. The ordinary seta; carry 

 some minute projections on the extremity which projects outwards, 

 while the internal extremity is attached to its sac by a congeries of fine 

 muscular threads. The tubercula pubertatis form a band on either side 

 the girdle, and occupy segments 23, 24, 25, or in some cases segments 

 23 to 26 inclusive. This point needs fuller investigation. I have found 

 both arrangements, but am at present unable to say whether there is 

 specific difference between the two forms. 



The colour varies considerably, on which account Eisen has distin- 

 guished a type and varieties. The type is usually sienna brown, darker 

 in front, with lighter girdle, and the tail often of a fleshy brown, or 

 tending to green. It undoubtedly simulates the colour of its surround- 

 ings, or is able to bring about a close resemblance between its body- 

 colour and the colour of the soil or vegetatiou amid which it resides. 

 The worm is exceedingly active, and is able to move rapidly backwards, 

 a mode of locomotion which it seems to prefer to direct progression. 

 I have not found allusion in any w^riter to the spermatophores which 

 the animal carries about during the breeding season. I have found them 

 repeatedly affixed to the ventral surface, usually about segments 19 or 20. 

 Internally I find spermathecae in segments 9 and 10, and the crop and 

 gizzard as in Lumbricus. In this I differ from Beddard, whose Teneriffe 

 species comes nearer to the third British species mentioned below. Total 

 number of segments — 60 to 90, or about twice as many behind the girdle 

 as before it. 



The egg-capsules of this worm are to be found in great abundance at 

 almost every season of the year. They are small, and of an olive-green 

 colour. The young seem to reach an adult condition very early, and 

 this fact, together with the power to go rapidly backwards, and the 

 almost complete encirclement of the body by the girdle, seems to point 

 to a primitive type, and indicate that Alhirus is a surviving link by which 

 to connect our earthworms with their progenitors of aquatic habit. 



The synonyms are numerous. 



1829. Enterion tetraedrtim, Savigny, " Histoire des Progres des Sciences 



Naturelles" (Cuvier), ser. 11, vol. iv., p. 17. 

 1837. Ltimbriais tetraedrus^ Duges, Annales des Sciences Nat. ser. il., vol. 



viii., pp. 17-23. 

 1843. Lumbricus agilis, Hoffmeister, Wiegmann's Archiv. fiir Naturge- 



schichte, p. 191, Tab. ix., fig. 6; also " Familie der Regen- 



wiirmer," 1845, p. 36, fig. 8. 

 1851. Lumbricus tetraedrus, Grube, "Die Familien der Anneliden," pp. 



99. 145- 

 1861. Liwibricus tetraedrus, Johnston, " A Catalogue of British Worms," 



p. 61. 

 1870. Lufnbrictis tetraedrus, 'Bis&n, Ofversigt af K. Vetensk.-Akad.,Y>- 99^-']' 

 1873. Alhirus tetraedrtis, Eisen, Ofversigt af K. V.-Akad., No. 8, p. 54. 

 1884. Allurus tetraedrus, Rosa, " I lyumbricidi del Piemonte," p. 51. 



