British Enchytrxids. By Rev. H. Friend. 579 



II. — Some Genus Characters. 



It may be helpful to students if, before describing and cata- 

 loguing the species, I state some of the distinguishing marks of a 

 Henlea. It will be best to give first of all the characters which 

 Michaelsen {2) held to be of importance. His diagnosis of the 

 genus is as follows : " Setfe straight or slightly bent to form an 

 old-fashioned /. Small head-pore opening between the prostomium 

 and the peristomium, or first body segment. No dorsal pores are 

 present. The coelomic corpuscles are large, chiefly discoid, seldom 

 elliptical, and darkly granular. The resophagus merges suddenly 

 into the intestine in the 7th, 8th, or 9th segment. The origin of 

 the dorsal vessel is anteclitellian, occurring in the 8th or 9th 

 segment. The blood is colourless, and there are no heart-like 

 enlargements of the vascular system. The anteseptal of the 

 nephridia is small and simple, there are massive gonads, and the 

 spermathecie, which communicate with the oesophagus, are simple 

 organs, destitute of diverticula." 



Beddard's description {-3) is more brief ; but while it omits 

 some of the foregoing details, it adds one or two others which are 

 of interest. He says (p. 349) : " Set^e different in form and 

 arrangement, according to the species. Head pore between pro- 

 stomium and buccal segment ; no dorsal pores. Qj^sophagus 

 sharply marked off from the intestine. Dorsal vessel arises in 

 front of the clitellum ; blood colourless. Duct of nephridium 

 springs from the postseptal portion near to the septum." Nothing 

 is said in either of these definitions about the brain, the septal 

 glands, the salivary glands, or the oesophageal glands, but Beddard 

 adds a note which is suggestive. " This genus," he says, " has 

 been recently instituted by Michaelsen in his synopsis of the 

 family. It forms undoubtedly a somewhat heterogeneous assem- 

 blage of species, which are chiefly bound together by the fact that 

 the oesophagus is distinctly separated from the intestine by a 

 constriction, and by the anteclitellian origin of the dorsal vessel ; 

 as a rule, there are oesophageal glands at the commencement of the 

 intestine; all these points ally the genus Henlea to the genus 

 Bvchholzia. There appear to be no other characters distinctive of 

 the genus ; some have and some have not salivary glands ; If. 

 puteana has two pairs of spermathecfe, which is unique in the 

 whole family ; this species also has straight setse like those of the 

 genus Enchytrxus, while in H. dicksonii the set?e are /-shaped, as 

 ■ in the genus Pachydrilus." 



I do not think anything would be gained in the present state 

 of our knowledge, or ignorance rather, by a new attempt at 

 definition. As our knowledge becomes more perfect it may be 

 found necessary again to divide up the genus, and make the 

 boundary lines more sharp. It must be noted, however, that some 



2 R 2 



