Alien OligocJuvts in England. By Rev. H. Friend. 271 



On the other hand, the recent additions to the list of species 

 include many forms which differ widely from the type. As under- 

 stood to-day, the genus Dicliogastcr may include worms which 

 have either one or two pairs of spermathecse, one, two or three 

 pairs of prostates, penial setae present or absent, spermathecse with 

 or without diverticula, girdle saddle-shaped or ring-formed, either 

 two or three pairs of oesophageal glands, and a number of other 

 variations. I do not know of any character in the worm under 

 consideration which makes it impossible for it to fit into this 

 genus, or which would ally it more closely to any other. Our 

 information about the presence or absence of a tongue or taste 

 organ, and the existence of one or more peptonephridia in other 

 species is not very complete, but these are not generic differences.* 



If we sum up the most important points we shall be able to 

 discover what species come nearest to D. lage^iiformis. There are 

 two pairs of spermathecce and two pairs of prostates. There are no 

 penial setse, and the diverticula of the spermathecai are only 

 imperfectly developed. There are three pau-s of oesophageal glands, 

 the girdle covers segments 13-20, and the oviducts have but one 

 pore. In some of these particulars D. ciBcifera, in others D. incrmio 

 and D. heteronejjhra are related thereto. But these are all very 

 large worms, while our present species is a pigmy, and they vary 

 in many other ways as well. 



D. lageniformis must therefore, for the present, be regarded as 

 occupying a position somewhat apart, the difficulty of placing it 

 being enhanced by the fact that we have no clue to its original 

 home. 



Y. — Bibliography. 



1. 1888. Beddard — Quart. Journ. Micr. Sci., xxix. pp. 235-82 (2 pis,). 



Structure of Urochcefa and Dicliog aster. 



2. 1895. ,, A Monograph of the Order Oligochaeta. 



3. 1886. Benham — Quart. Journ. Micr. Sci., xxvii. pp. 77-103. Studies on 



Earthworms (p. 94). 



4. 1890. ,, Quarb. Journ. Micr. Sci., XXX. pp. 201-315. An Attempt 



to Classify Earthworms. 



5. 1915, Friend— Ann. Applied Biol., ii. pp. 195-208 (6 pis.). Studies in 



Enchytmeid Worms : Henlen fragilis Friend. 



6. 1916. ,, Journ. R. Micr. Soc. Alien Oligochiets in England : 



Kerria rubra sp, n. 



7. 1889. MiCHAELSEN — Jahrb. d. Hamburg wiss. Aust., vi. 



8. 1891. ,, Jahrb. d. Hamburg wiss. Aust., ix. p. 66, 



9. 1891. „ Arch, fiir, Nat., p. 202. 



10. 1900, „ Das Tierreich : Oligochaeta, 



11. 1915. Stephenson — ^Mem. Indian Museum, vi. pp. 35-108 (4 pis.). On 



Some Indian Oligochaeta, 



See Benham, Quart. Jouru. Micr. Sci., xxxi. (1890) pp. 288-89, 



U 2 



