STRUCTURE OF EARTHWORM OE GENUS DIACH^TA. 173 



It may perhaps be considered that the points of diflference 

 enumerated in the above Table are sufficient to distinguish 

 generically all three forms ; but I defer the discussion of this 

 matter until something is known about the structure of other 

 allied forms, which may occur in the West Indies. It is to 

 be noted, however, that the species, which for the present I 

 refer to the genus Diachseta, although much specialized in 

 the shape of the setae, and in the loss of the setse of the ante- 

 rior segments, connects in some ways (e.g. in the structure 

 of the generative organs) the genus Urochseta with allied 

 forms, such as Geoscolex. 



List of Memoirs referred to. 



1. Beddakd, F. E.— " On the Tail Bristles of a West Indian Earthworm," 



' Nature,' vol. xxxix, p. 15. 



2. Beddard, F. E. — " On the Structure of a New Genus of Lumbricidse 



(Thamnodrilus Gulielmi)," 'Proc. Zool. Soc.,' 1887, p. 154. 



3. Beddard, F. E. — " On the Specific Characters and Structure of Certain 



New Zealand Earthworms," 'Proc. Zool. Soc.,' 1885, p. 810. 



4. Beddard, F. E. — " Note on some Earthworms from India," ' Ann. and 



Mag. Nat. Hist.,' ser. 5, vol. xii, p. 213. 



5. Benham, W. B. — " Studies on Earthworms," No. 2, ' Quart. Journ. 



Micr. Sci.,' vol. xxvii, N. S., p. 77. 



6. MtJiLER, Fritz. — "On Description of a New Species of Earthworm, 



Lumbricus corethrurus," 'Ann. and Mag Nat. Hist.,' ser. 2, 

 vol. XX, p. 13. 



7. Perrier, E. — "Recherches pour servir a I'histoire des Lombriciens 



terrestres," 'Nouv. Arch. d. Mus.,' t. viii (1872). 



8. Perrier, E. — "Organisation des Urochseta," 'Arch. d. Zool. Exp.,' 



t. iii (1874), p. 331. 



9. Rosa, D. — "Sulla Struttura dello Hormogaster Radii," 'Mem. R. 



Accad. Sci. Torino,' t. xxxix, ser. 2, p. 3. 



10. Rosa, D. — " Lombrichi raccolti nell' isola Nias, Sec." ' Ann. Mus. civ. 



Genoa,' ser. 2a, vol. vii. 



11. ScHMARDA. — • Neue wirbellose Thiere,' Bd. i, pt. ii. 



12. Spencer, W. B. — "The Anatomy of Megascolides australis," 



'Trans. Roy. Soc. Victoria,' vol. i, pt. i. 



