126 



15 (i6) Nephridia with a wide, closely wound canal and slight inter- 



mediate substance Mcsenchytrceus 



16 (15) Nephridia with narrow, loosely wound canal and well-developed 



intermediate substance Marionina 



HENLEA Michaelsen 



The genus Henlea was established by Michaelsen in 1889, and al- 

 though it includes a somewhat heterogeneous assemblage of species, 

 there does not seem to be at present sufficient grounds for breaking 

 up the genus into different generic types. It is distinguished from the 

 other genera by the following characters : ( i ) the sudden change in 

 the diameter of the digestive tract where the oesophagus passes into the 

 intestine; and (2) the anteclitellar origin of the dorsal vessel. As a 

 rule there are diverticula at the beginning of the intestine. The nearest 

 relative of Henlea is Bryodrilus, although Bnchholsia also stands close. 

 Michaelsen ('03b, p. 51), in discussing the phylogeny of the Bnchy- 

 trcridcc, placed Henlea at the base of the system, as the most primitive 

 genus, on the ground that the forms belonging to this group show the 

 greatest diversity in the character of the setae. Later the same writer 

 ( '05c, p. 24) described a new genus, Propappus, which is in a number 

 of respects more primitive than Henlea, and must be regarded as the 

 oldest of the known enchytr?eid genera. One of the striking charac- 

 ters of Propappus is the presence of forked set?e. 



Forty-two species and two varieties are assigned to Henlea at the 

 present time. Of this number seven are doubtful, either as regards 

 their being valid species, or on account of their generic assignment. 

 The following seem worthy of mention. H. lefroyi, described by 

 Beddard ('05, p. 62) from India and placed provisionally in this genus, 

 is said to have a dorsal vessel of intraclitellar origin, the intestinal di- 

 verticula lacking, and the oesophagus transforming gradually into the 

 intestine. Beddard found it possible to eliminate, by other characters, 

 all of the genera except Bryodrilus and Henlea. He places the species 

 in Henlea because the characteristic intestinal diverticula are some- 

 times absent — a reason which is open to question. H. schaiifi, de- 

 scribed by Southern ('loa. p. 18) from the White Mountains and 

 placed provisionally in this genus, is described as lacking intestinal 

 diverticula, and the oesophagus as passing gradually into the intestine. 

 The anteclitellar origin of the dorsal vessel seems to be the only good 

 ground for placing the species in this genus. 



Taking the genus as a whole, there is a remarkable variation in 

 the different organs. H. puteana Vejdovsky is unique in having two 

 pairs of spermathecae. The species of the genus can be grouped in 



