264 FEANK E. BEDDAKD. 



drilus Spegazziuii^ in which Rosa asserts the absence of 

 diverticula; as a rule this genus of course has diverticula. 

 In the absence of diverticula, and in the length of the 

 spermatothecae, P. lacuum resembles Gordiodrilus. If 

 Michaelsen had not described the genus Pygmseodrilus I 

 should certainly have referred the present species to that 

 genus. 



4. Siphonogaster Millsoni, F. E. B. 



Siphonogaster Millsoui, F. E. Beddard, P.Z.S,, 

 1890, p. 48. 



Two or three years ago Levinsen^ described a remarkable 

 worm from the banks of the Nile, characterised by having a 

 pair of long processes arising from the ventral side of the 

 body a little behind the head. A year ago I contributed to 

 the 'Proceedings of the Zoological Society' a short notice of 

 another worm, evidently referable to the same genus, from 

 Lagos, West Africa. I have lately, through the kindness of 

 Mr. Alvan Millson acquired a large number of examples of the 

 latter species, many of them in an excellent state of preserva- 

 tion for section cutting; I am able, therefore, to add some- 

 thing to the very fragmentary account I gave formerly of the 

 structure of Siphonogaster Millsoni. 



I shall give some of the most interesting facts in its 

 anatomy, and refer to the specific characters at the end of 

 the description. 



§ External Characters. 



The most striking external peculiarity of the Oligochsete, 

 which is of about the same bulk as the average-sized British 

 Lumbrici, is of course the pair of appendages already referred 

 to; they arise from the 18th segment. The appendages vary in 

 size in individuals, a variation which 1 take to be indicative of 



» "Om to iiye lleguormslaegter fra ^gypten," 'Videusk. Medd. Kjocbii., 

 1889. 



