388 OLIGOCHAETA cm 



Mliller. This worm, which is universal, or nearly so, in il 

 range, doubtless having been transferred accidentally from counti 

 to country, invariably shows a light spot not far from the tail 

 when this is examined with the microscope it is seen that tl 

 chaetae are here absent or very small, and that the muscuh 

 structure of the body- wall is slightly different ; it was thougl 

 that this spot was a zone of growth where fresh segments coulc 

 be added after the fashion of some of the aquatic Qligochaeta, 

 which, it may be remarked, the present genus shows a curioi 

 point of likeness in the bifid character of the chaetae. It seei 

 however, that there are really no grounds for the supposition, ai 

 it is possible that we have here a " weak " spot, such as that 

 the foot of certain land snails, which readily gives way when tl 

 worm is picked up by a bird, and allows the " better half " of tl 

 creature to escape. The Bermudian genus Onycliochaeta offers 

 very strange peculiarity in that the chaetae on the hinder se<; 

 ments of /the body are enormously larger than those in front, ai 

 end in strong hooks ; it seems likely that their function is 

 maintain a tight hold of the ground while the worm is leanii 

 out of its burrow, as every one has seen the common earthwon 

 of this country do. Onychochaeta has the same irregular arrant 

 ment of the chaetae upon the greater part of the body, as hi 

 Pontoscolex. This family, like so many others, has its giants ai 

 its dwarfs. At one extreme is the great Antaeus of Sout 

 America, several feet in length ; at the other the inch-long Bye 

 genia of Africa. The American Urolerms has a pair of intestii 

 caeca like those of Pqrichaeta, and placed in the same segment. 



Fam. 14. Lumbricidae. 1 This family is to be distinguish* 

 by the following assemblage of characters. 



The male pores are usually upon segment 15, and nevt 

 behind that segment ; the clitellum commences some way behii 

 the male pores. The gizzard, which is invariably single, is equally 

 invariably at the end of the oesophagus. There are three pairs 

 of calciferous glands. The nephridia are always paired. The 

 spermathecae never have a diverticulum. 



This family only contains three well-known genera, viz. 



1 Rosa, "Revisione dei Lumbricidae," Mem. Ace. Torino (2), xliii. 1893, p. 399 ; 

 also the Rev. H. Friend's numerous and useful papers, and especially "A Hj! 

 Species of Earthworms," Proc. Hoy. Irish Ac. (3) ii. 1891-93, p. 402 ; and ' : The 

 Earthworms of Ireland," Irish Nat. v. 1896, p. 69, etc. 





