46 W. BALDWIN SPENCER. 



lining, though usually this cannot be detected ; and in this 

 respect the duct shows a marked difference when contrasted 

 with either the spermathecae or the fine duct opening into 

 ' these or the vagina. 



External to this layer of cells lies one of muscle- fibres, which 

 are directly continuous with those of the spermathecae. Where 

 the duct comes in contact with the latter the fibres are espe- 

 cially well developed, and form, as described by Hoyle^ in P. 

 protelis, a strongly muscular papilla projecting into the 

 cavity of the spermatheca, and pierced by a fine tube with a dis- 

 tinct chitinous lining. There is not visible externally a somewhat 

 spherical bulb such as is figured by Leuckart in P. tsenioides 

 and subuliferum,^ nor is there any swollen part of the duct 

 close to this. External to the muscle layer there lies on the 

 anterior, dorsal, and ventral surfaces, save in the very median 

 line where the two join together beneath the oviduct, a remark- 

 able layer of cells, similar, as pointed out by Leuckart, to those 

 found in a portion of the male ducts. The cells vary in size 

 and are irregularly arranged (fig. 54, Sp. Gl.) ; each contains 

 a large nucleus, which rarely shows a nuclear membrane, and 

 stains deeply with borax carmine. The whole cell is filled by 

 a structure having the appearance of a network, in the meshes 

 of which material of a homogeneous nature is present. Both 

 take stain, the network more deeply. These cells, especially in 

 the nature of their nuclei, resemble somewhat those of the 

 hook-glands, but are precisely similar to certain others which 

 will be described later in connection with the male organs. 



Leuckart has described a special network of nerve-fibres in 

 connection with this part, but of these I have been unable to 

 determine the presence in this particular form. 



On the dorsal portion of the wall where the two tubes unite 

 in the median line, and immediately above the opening of the 

 vagina and posteriorly to that of the oviduct, there lie two small 

 tubular diverticula, similar in the main to those present in 

 other forms, but apparently smaller than in any yet described. 



' Loc. cit., p. 187. 



2 Loc. cit., Taf. ii, figs. 17 and 19. 



