AN ATTEMPT TO CLASSIFY EARTHWORMS. 253 



The clitellura, incomplete ventrally, commences in front 

 of Somite xviii^ and occupies ten or more somites. 



The spermi ducal pores are behind Somite xviii (with 

 the exception of Hormogaster), and are usually nearly in 

 the middle of the clitellum. 



There are two or more pairs of sperm-sacs^ and two pairs 

 of testes and rosettes. 



The spermathecse are either small, or if large are quite 

 simple, without appendices. 



The gizzard is in front of Somite x. 



Nephridia are provided with a large duct, usually produced 

 into a caecum; nephridiopores are in a line with the outer 

 couple of setae (except in Hormogaster). 



Genus 24. Rhinodrilus, E. P., 1872 (= Thamnodrilus, 

 Beddard, 1887). 



Prostomium is two or three times longer than the first 

 somite [and can be withdrawn into the buccal cavity ; at any 

 rate, it is so in spirit specimens]. 



The setae are ornamented near their distal ends with 

 several rows of crescentic ridges, which are slightly more 

 marked in the clitellar setae. 



The clitellum, which does not extend across the ventral 

 surface, occupies seven or more somites, xv to xxv (xx — xxvi, 

 Horst). Along its ventral boundary, on each side, is a glan- 

 dular band — tubercula pubertatis — on Somites xx — xxv. 



The spermiducal pore is intersegmental between xx and 

 xxi (according to my own observation) (xix/xx, E. P.). 



The nephridiopores are in a line with the outer setae. 



Sperm-sacs are two pairs, in Somites xi, xii, with median 

 sacs. 



[Two pairs of testes and ciliated rosettes in Somites xi, xii. 



Spermathecae are long and club-shaped, in Somites vii, 

 VIII, IX (Horst), or globular, in Somites v to viii, in a species 

 examined by myself. 



The nephridium has only a short and slightly coiled 

 tubule; the duct is produced into a caecum. The anterior six 



