:>7> ME FRANK E. BEDDARD ON THE ANATOMY OF OCNERODRILUS. 



(2) a pharynx with muscular walls, extending from this point to the end of the Vth 

 segment ; (3) a narrow oesophagus with much-folded walls, which become widened out in 

 the Vlllth segment, where it receives (4) a pair of calciferous glands. (5) The ciliated 

 intestine is a very narrow tube in segments IX and X, after which it is suddenly widened 

 but has no typhlosole. 



The brain lies between segments III and IV. 



The vascular system is chiefly remarkable for the presence of two large hearts — one 

 pair in the Xth, the other pair in the Xlth segment. 



The nephridia are paired, and exist in all the segments from the Illrd ; in some of 

 the genital segments they become degenerate, viz., the Xlth and Xllth. 



The reproductive organs consist of (1) two pairs of testes in segments X and XI, 

 attached to the front wall of the segment ; (2) of a pair of ovaries occupying a correspond- 

 ing position in segment XIII ; (3) of vasa deferentia, which open into the segments 

 containing the testes, and pass back, becoming fused, to open on to the exterior in 

 common with (4) the atria, which are long, often coiled, tubes, divisible into a muscular 

 and a glandular portion. The epithelial lining consists throughout of a single layer of 

 cells ; (5) the oviducts open into the XHIth segment by a funnel, and on to the exterior 

 of segment XIV. There are no egg-sacs, and the ova are of comparatively large size 

 and few in number. (6) One pair of spermathecce, without diverticula, exist in 

 segment VIII. 



II. Systematic Position of Ocnerodrilus. 



In discussing the affinities of Ocnerodrilus I shall pass over the question of 

 Claparede's division of the Oligochseta, since most of those who have subsequently 

 studied the group agree in rejecting it. Eos a, however, retains the Terricolse. As I have 

 already pointed out [3], his definition of this group hardly excludes Phreorycles, 

 which is indeed a link between the Lumbriculidse and certain Earthworms. 



The most recent contribution to this question is a paper by Benham [9], chiefly 

 devoted to the classification of Earthworms, but containing also some observations upon 

 the major divisions of the group Oligochseta. 



Mr Benham divides the Oligochseta into two sub-classes, viz., Naidomorpha and 

 Lumbricomorpha, to be distinguished by the occurrence or non-occurrence of asexual 

 reproduction.* 



There are few other points which distinguish these groups. Mr Benham mentions the 

 situation of the male genital pores upon or in front of segment VII, the colourless blood, 

 and the frequent " cephalisation." 



We must strike out the second character, since the blood is coloured in Naids ; 'also 

 the third character, on account of the absence of setae on the anterior segments of 

 'Jnijcliocltajta and Deodrilus (Beddard, Nos. 6 and 7). 



* We require, however, more information about Ilyodrilus, which resembles the Naidomorpha in certain points. 



