DESCRIPTIONS OF EARTHWORMS. 293 



belonging to a genus , the other species of which are cha- 

 racterized by the presence of only a single gizzard. Prom 

 this fact we may infer, that it is not permitted to consider 

 such characters as marks of generic difference , if they are 

 not accompanied by other characters , especially by those 

 relating to the generative system. Therefore I am inclined 

 to assume , that the worm , described by Mr. Benham ') 

 as Trigaster Lankesteri, which agrees in its main characters 

 with Acanthodrilus , except in the presence of three giz- 

 zards , really belongs to this genus. 



The vascular system possesses a dorsal vessel, being a 

 single tube , which communicates with the ventral trunk by 4 

 pairs of transverse hearts, situates in segment 6, 7, 8 and 

 9; from the third of these commissural vessels a strong 

 branch arises , running along the anterior side of the 8th 

 mesentery. In the 10th, 11th, 12th and 13th ring there 

 are situated large abdominal hearts, which arise from the 

 supra-intestinal vessel and communicate by a small branch 

 with the dorsal trunk. Moreover in the 10th segment a 

 pair of lateral vessels arises from the dorsal side of the 

 intestine; they run forward along the side of the gizzards 

 and communicate with each other by a transverse vessel 

 in the 7th ring. The lateral vessels agree much in their 

 arrangement with those of Ac. Schlegelii. 



As stated in my first note, we find in the 13th seg- 

 ment a pair of vesiculae seminales, containing spermatozoa 

 in different stages of development (fig. 5). 



The ovaries are situated in the 14th segment; they have 

 the appearance of a rather broad , ribbon-shaped body, 

 showing numerous folds , radiating from its base. The basal 

 portion of the ovary consists of indifferent germinal cells, 

 while its inferior half contains several fully developed eggs, 

 lying each in a well-defined capsule of connective tissue 

 (fig. 6). 



In stead of the real segmental organs we find in each 



1) Quart. Journal of Micro3c. Science, Vol. XXVII, 1887, p. 94. 

 Notes from the Leyden IVTiTseiim , Vol IX. 



