696 OLIGOCHAETA 



(2) AUurus neapolitanus. Clit. xxi-xxv, Tub. pub. xxi-xxtv. 

 (a) cj pore on xiii, A. neapolitanus. 

 {&) (J pore on xv, A. ninnii. 



MiCHAELSEN argues that, since in A. kercynius it is the male pore only which 

 has a different position, the other organs being as in A. tetraedrus, and since in 

 a variety of Alloldbophora putris, the female as -well as the male apertures had 

 been shifted, the position of the male pore in A. hercynius is a valid specific 

 distinction. If so, then one of the varieties of Periomyx excavatus, in which the 

 male pores are normal in position but the female pores abnormal, should be regarded 

 as entitled to specific rank. 



Friend has added three other species, viz. A. tetragonurus, A. flavus, and 

 A. macrurus. Pending further information, A. macrurus seems to be a valid species 

 on account of the very forward position of the clitellum (xv-xxii). 



A. tetragonurus is probably, as Rosa thinks, merely a form of TetragovAirus pupa. 



Vaillant, in his work on the Oligochaeta (6, p. 151, &c.), allows five species, 



which are — 



(i) AUurus tetraedrus {=L. agilis, Hoffm.), (Sav.). 



(2) AUurus amphisbaena (DuG.). 



(3) AUurus phosphoreus (Dug.). 



(4) AUurus brevieoUis (FiTZ.). 



(5) AUurus brevispinus (Gekstf.). 



No. 3 has already been relegated to the genus Pontodrilus (see p. 472). 



A. amphisbaena and A. brevieoUis are probably referable to AUurus. As to the 

 first it is usually regarded as a synonym oi A. tetraedrus. But, as Vaillant points 

 out, the prostomium completely dividing th^ buccal lobe is in the way of this 

 identification; so, too, is the size (?) 810 mm.^ A. brevieoUis has not paired setae, 

 but in other respects seems to be probably referable to AUurus. A. brevispinus is 

 very doubtful; there is no information as to clitellum or male pores. 



It will be safest, in my opinion, to regard only two species as firmly established 

 until further data are forthcoming. In this case the occasional presence of the male 

 pores upon segment xv will be merely a variation. 



(i) AUurus tetraedrus (Savigny). 



Bnterion tetraedrum, J. C. Savigny, Mdm. Ac. Roy. Inst. Fr., 1826, p. 184. 

 Iiumbrieus tetraedrus, A. Dug:&s, Ann. Sci. Nat., 1837, pp. 17 and 23. 

 A. tetraedrus, G. Eisen, Ofv. svensk. Akad., 1874, No. 2, p. 54. 

 ' Rosa gives 810 mm.; DuGis, 80 mm. The former measurement is very probably a printer's error. 



