Benham. — On Earthworms. 131 



which is an oval glandular patch, extending up to the level 

 of chaeta c. Each oval patch really consists of a crescentic 

 patch on the hinder edge of 7, and another on the anterior 

 edge of 8 (and so with segments 8 and 9). In addition to 

 these there is a similar oval " tuberculum pubertatis," or 

 "genital papilla," on the intersegmental grooves 9/10, in a 

 line with chaeta a. Thus there are three pairs of preclitellian 

 " tubercula pubertatis." 



Nephridiopores in a single series in line with chaetae b. 

 They are invisible externally in the preserved worm, but can 

 be traced from within. 



Internal Anatomy. 



Septa forming the posterior boundaries of segments 

 7 to 14 inclusive are more or less thickened. 



Vascular System. — The dorsal vessel is completely dupli- 

 cated, not uniting to pass through the septa. There are four 

 pairs of "intestinal hearts" in segments 10 to 13, and a 

 smaller " lateral heart " in the 9th segment. 



Alimentary Tract. — The gizzard is in segment 6 ; the 

 oesophagus is dilated in segments 15 and 16 : it has here 

 highly vascular and lamellate walls, but is without any lime- 

 particles. The oesophagus thence narrows to the 19th 

 segment. The intestine commences in segment 20, and is 

 without a typhlosole. 



Nephridia. — The worm is meganephric, the organs being 

 in a single series. One peculiarity is to be noted — viz., the 

 absence of a muscular duct. The nephridia of the segments 

 3, 4, 5 are large and pink. I traced their ducts to the body- 

 wall, and saw none entering the buccal region of tbe gut. No 

 doubt they junction as " peptonephridia." 



Reproductive Organs. — The two pairs of testes lie in 

 segments 10 and 11, free in the coelom, attached to the 

 anterior wall. The sperm-sacs are in three pairs, those in 

 segments 9 and 10 attached to hinder septum, and a larger 

 pair attached to the front septum of the 12th segment. The 

 spermiducal glands are thick, much convoluted tubes, com- 

 pressed and compacted to form, apparently, a lobed mass. 

 Each is confined to its own segment. The duct is short and 

 narrow. Penial chsetae are absent. Spermathecae : Two pairs 

 in the usual segments ; each is a simple ovoid sac, with 

 a rather prominent equatorial region, the proximal portion 

 being rather more muscular than the distal. There is no 

 definite duct. There is no diverticulum ; and sections demon- 

 strate that none exists embedded in the body-wall. The 

 simple character of this organ suggests its specific name, for, 

 without exception, I believe, members of the genus Acantho- 

 ■drilus (s.l.) have a diverticulum. 



