198 Studies in Enchytraeid Worms 



the species which have no oesophageal glands Henleanella, and thus 

 reserving the term Henlea exclusively for those species in which oeso- 

 phageal glands exist. The forms which depart from these two divisions 

 by showing the origin of the dorsal vessel in the region of the clitellum 

 might possibly be arranged in a third group as Henleana. In the 

 present paper, however, I do not propose to discuss these forms, bat 

 to confine myself purely to those species which, having oesophageal 

 glands on or near the 8th segment, where the dorsal vessel takes its 

 rise, may be regarded as true or typical species. 



Henlea thus shorn of doubtful characters would reveal the following 

 points : 



1. Generic. Glands or diverticula (Darmtaschen or oesophageal 

 glands) arising from the oesophagus in or near segments 7, 8 or 9, and 

 varying in number from one (H. moderala Welch) to four (H. ventri- 

 culosa d'Ud.) 1 . Dorsal vessel anticlitellian, arising immediately behind 

 the oesophageal glands. Oesophagus passing sharply into the intestine 

 where the glands open into it. 



Coelomic corpuscles (Lymphkorper) of one form, large, discus- 

 formed or broadly elliptical, darkly granulated. Brain slightly longer 

 than broad, concave or incised before and behind. 



2. General. Setae straight or slightly curved within, varying both 

 in number and length; often Fridericia-like, i.e. with the shortest in 

 the middle of the bundle. Small head pore, situated between the 

 prostomium and the first body segment or peristomium, and represented 

 by the sign 0/1. Dorsal pores absent. Blood colourless; vascular 

 system destitute of the so-called heart-body (Herzkorper), though the 

 dorsal vessel is often enlarged in segments 6 to 9. 



Nephridia with small anteseptal portion, the postseptal changing 

 into the duct immediately behind the septum. Spermathecae con- 

 sisting of a sac-like body, usually with a swollen portion or ampulla ; 

 glands at the opening in intersegment 4/5 sometimes present, diverticula 

 rare (not yet found in any British species), the posterior portion of the 

 spermatheca attached to the oesophagus or opening into it. Salivary 

 glands present. Three pairs of septal glands in segments 4/5, 5/6 and 

 6/7. Sperm funnels in the 11th segment with duct ending in the 

 penial bulb on the ventral side of segment 12. Oviduct aborted, the 

 oviducal pore being usually invisible. 



It will be seen that one or other of the foregoing general characters 



1 These glands are dorsal to the oesophagus, whereas in Kerria, for example, they are 

 ventral. 



