XIII 



MEGADRILI 



387 



in any undoubted Lumbricid. The peculiar elongated cocoon, 

 which much resembles that of Sparganophihis, is another char- 

 acter which favours its Geoscolecine affinities. Dr. Michaelsen has 

 proposed to unite Criodrilus and Alma into a family intermediate 

 between the Geoscolicidae and the Lumbricidae. 



Perhaps the most remarkable genus in the whole family is 

 Alma. One species lives in the Nile mud; another is the 

 " Yoruba worm " of West Africa, whose habits have been de- 

 scribed by Mr. Millson. The most marked character of this genus, 

 apart from the branchiae (see p. 352) which apparently may be 



Fig. 198. Alma millsoni F. E. B. 



present or absent according to the species, is in the two enormous 

 processes of the body-wall, which are illustrated in Fig. 198. 

 These contain the sperm-ducts, which, however, open some way 

 in front of the free end ; they are provided on the ventral surface 

 with a series of sucker-like structures and with peculiar chaetae. 

 Another interesting genus is Pontoscolex, which was originally 

 described from the sea-shore of Jamaica by Schmarda ; there are 

 only two species which are certainly characterised, though a variety 

 from the Hawaian Islands may be a " good " species. It possesses 

 the remarkable peculiarity that the chaetae at the end of the 

 body are disposed in a perfectly irregular fashion, which earned 

 for it the name of brush-tail at the hands of its discoverer, Fritz 



