AN ATTEMPT TO CLASSIFY EARTHWORMS. 257 



Sperraathecse small ; two or three pairs on hinder margin of 

 Somite xi. 



Two pairs of nephridia in each somite, each a simple 

 tubule without a distinct duct. 



[Sixteen globular " albumen-glands '^ are present, as four 

 sacs on each side of Somites x, xi. 



Ovaries in Somite xii.^ 



The worm is very short in proportion to its width.] 



See Benham, 'Zool. Anzeiger/ 1888, No. 271. 



Remarks on Rhinodrilidse. 



I include in this family the remaining genera grouped by 

 Rosa in his Geoscolecidse ; the two families together nearly 

 correspond with Perrier's " intraclitellian worms.^' 



The most aberrant form is Hormogaster, with its male 

 pores far forwards, and nephridiopores in line with the inner 

 couple of setse. In these two points, showing a decided 

 affinity to Lumbricus, and perhaps it belongs to the family 

 Lumbricidse. 



Brachydrilus is of interest in possessing two pairs of 

 large nephridia in each somite ; evidently an intermediate 

 condition between a network in which the tubules have 

 become grouped, as in Cryptodrilus, into three masses on 

 each side, and the ordinary condition of a pair of nephridia. 

 It is quite conceivable that, as in Megascolides, one tubule 

 becomes gradually larger, whilst at the same time the rest 

 become fewer, in some other form two such tubules might 

 increase in size, and so result in two pairs of nephridia per 

 somite. 



The testes and spermiducal pores have abnormal positions 

 very usually in this family; for instance, in Microchseta testes 

 and ovaries are placed one somite further forwards than is 

 normally the case;^ in Urobenus and Rhinodrilus the 



^ The fusion between peristomium and first setigerous somite appears 

 complete. 

 2 See foot-note on p. 254:. 



