A KEY TO BRITISH HEN LEAS. 91 



-. ,- | Two pairs of oesophageal glands H. ventriculosa. 



(One pair of oesophageal glands 16 



-, n ( Glands in segment 7 17 



( Glands in segment 8 19 



-. 7 ( Dorsal vessel in 7-8 18 



\ Dorsal vessel in 8 H. nasuta. 



-. r, f Salivary glands present H. attenuata. 



( Salivary glands absent H. heterotropa. 



( Two pairs septal glands H. fridericioides. 



19 - Three pairs septal glands 20 



(Four pairs septal glands H. quadruplet. 



[Dorsal vessel arises in 8 H. pusilla. 



20 \ Dorsal vessel arises in 8-9 21 



(Dorsal vessel postclitellian H. triloba. 



91 j Sperm-funnel about 2 x 1 H. fragilis. 



\ Sperm-funnel about 4 x 1 H. hibernica. 



In conclusion, a few special features may be pointed out. 

 Henlea puteana alone has two pairs of spermathecse, and H. 

 ventriculosa is the only known species with two pairs of oesopha- 

 geal glands. H. alba and H. inusitata have abnormal glands, 

 which may be oesophageal or salivary. In H. fridericioides and 

 H. mariona there are only two pairs of septal glands, but one is a 

 member of the Henlean group, the other belongs to Henleanella. 

 In certain cases the dorsal vessel arises in or behind the girdle. 

 At present H. triloba stands alone in this respect in the Henlean 

 group. Some of the species have the duct of the nephridium 

 arising near the septum, in others it is posterior, and in others 

 it has a median origin. The spermatheca^ present great variety, 

 but they never have diverticula, as in Fridericia. 



Bibliography. 



1. Friend, ' Zoologist,' 1911, pp. 464 seq. 



2. Friend, ' J. K. M. S.,' December, 1912. 



3. Friend, ' Irish Naturalist,' 1913, p. 9. 



4. Friend, 'Notts Naturalist Society,' 1913. 



5. Michaelsen, * Das Tierreich,' 1900. 



6. Southern, 'Proc. Roy. Irish Acad.,' vol. 27. 



