86 ANNELID OBTAINED DURING THE " SKEAT EXPEDITION." [Feb. 5, 



it is of larger calibre, and the cells are not so thoroughly stained by 

 the carmine ; it is, in fact, of a more glandular appearance. This 

 section of tube widens a little before it becomes continuous with 

 the first part of the spermiducal gland proper. The latter is quite 

 different again from the terminal part of the spermiducal gland, a 

 fact which appears to distinguish B. iris from B. vejdovskyanum. 

 In the latter there is, judging from Stoic's figure, no difference 

 whatever between the proximal and the distal regions of the spermi- 

 ducal gland. In the species with which I am here concerned, the 

 proximal section of the glandular tube is of rather limited extent. 

 Its lumen is fairly wide and is lined by tall columnar cells, which are 

 crowded with rounded spherules of secretion. They are not much 

 stained. In Stoic's figure the "paratrium" is represented as 

 arising from the terminal male tube at about halfway between its 

 commencement and the external orifice. In B. iris the same is the 

 case, and the point of origin nearly represents the passing of the 

 purely glandular part of the spermiducal gland into the distal 

 region, which has quite other characters. The distal part of the 

 tube is wide and has collapsible walls, a fact which is due to 

 their thinness. The epithelium lining the tube here is quite non- 

 glandular. It is a low columnar epithelium which is covered 

 externally by a rather lax covering of muscles. 



The paratrium has the egg-shaped form which it exhibits in the 

 other species of the genus. , There is, however, no cap of divergent 

 *' prostatic •■' cells such as are figured in B. vejdovski/anum. The 

 paratrium has very thick muscular walls, and its lining of cells 

 becomes deeper and more glandular in appearance at the blind end 

 of the sac. 



Where the spermiducal glands open on to the exterior of the 

 body they naturally have to burrow beneath the nerve-cord. The 

 latter is raised to near the intestiue, and a slip of muscles forming 

 a thick septum connects it with the ventral body-wall after the 

 two spermiducal glands are separated from each other. 



The ovaries lie in the xiith segment ; but I have not discovered 

 the oviducts. 



The genus Botlirioneuron may be defined and its species discri- 

 minated as follows : — 



Grenus Botheioneubon, Stole. 



Tubificids of 40-50 mm. in length. Sette entirely uncinate. 

 Prostomnim with an unpaired, often asymmetrical sense-organ \ 

 Male pore single and median or paired ; atrium with a lateral diver- 

 ticulum, the paratrium. Spermathecw absent. Ovidncal pores 

 pau-ed -. Spermatophores of peculiar form attached to neighbour- 

 hood of male orifice. 



Hah. Europe ; S. America ; Malay Peninsula. 



^ Fide moh^thm, "Oligocbajten" in ' Tierreich,' Berlin, 1890, for state- 

 ment that the sense-organ cliaractei-izes the genus. I am unable to read Stoic's 

 paper, which is in Bohemian. 



- In B. vejdovsl'yamm. They are not known in the other species. 



