AN ATTEMPT TO CLASSIFY EARTHWORMS. 251 



" Pyriform " sacs occur in posterior part of tlie body^ on the 

 ventral surface.] 



(N.B. — The enumeration of the somites is given differently 

 by the three authors who have described Urochseta. Rosa 

 has pointed out that there is some reason to believe that 

 Perrier counted a portion of the extended buccal region as the 

 first somite ; with the result that his first setigerous somite, 

 instead of being the second, as in all other worms, is the third ; 

 hence it becomes necessary to subtract one, in some cases, from 

 Perrier's numbers. Beddard has elucidated the position of 

 the gonads by means of longitudinal sections — the only reliable 

 means of deciding their position ; and on this point I have 

 followed him. The position of the external organs, and some 

 of the internal structures, I have been able to decide for myself 

 by an examination of some specimens kindly given to me by 

 Mr. W. Sclater, who obtained them in Demerara.) 



Species 1. U. corethrura, Fr. Muller, 1857; Brazil, Java, 

 Martinique, Fernando Noronha, and Aus- 

 tralia. 

 2. U. dubia,Horst; Sumatra. 



See Perrier, ' Arch, de Zool. Exp. et Gen.,' iii, 1874 ; Beddard, 

 ' Proc. Hoy. Soc. Edin.,' 1887 ; ' Quart. Journ. Micr. Sci.,' 

 xxix; Eosa, ^Ann. d. Mus. Civ.,' Geneva, viii, 1889. 



Genus 23. DiACHiET^L, Benham, 1886. 



Set 86 8, separate, alternate from somite to somite through- 

 out the body, except Seta 1, which always I'etains a linear 

 arrangement. 



Clitellum complete ; covers Somites xx to xxxiii, inter- 

 segmental grooves distinct all round. 



Spermiducal pores on Somite xxii ; no penial setse. 



Sperm-sacs extend through Somites xii to xxxviii.^ 



Nephridiopores in front of the outer setae. 



[No prostomium. 



Testes (?) and ciliated rosettes in Somite xi. 



' la a paper by Beddard (a proof of wliicli Prof. Lankestcr has kiudly 

 allowed me to see) on a uew species of this genus, two pairs of sperm-sacs 

 are described. 



