72 W. BALDWIN SPENCER. 



dilator rod-sac tlirougli which the cirrus passes, i. and o. Two layers of 

 cirrus. M. D. R. S. Muscular mass of dilator rod-sac. N(/. Nerve f^anglion. 

 CEs. CEsophagus. 0. D. Oviduct, 0. Sp. Duct of spermatheca. Sp. Sperma- 

 theca. S. Outer cavity of cirrus bulb. *S". Central cavity of cirrus bulb. 

 To. Tongue-like organ in dilator rod-sac. V. D. Vas deferens. /. Ventral 

 nerve cord. 



Fig. 60. — Horizontal longitudinal section through a portion of a mature 

 female ventral to the mid-gut to show the relative positions of the main nei-ve 

 mass, oesophagus, oviducts, and spermathecee. On one side a small portion 

 of the spermathecal duct is cut through close to its opening into the sper- 

 matheca. The double nature of the ganglionic mass is clearly marked, and 

 the absence of any ganglionic swelling in the oesophageal commissure. Zeiss, 

 A, oc. 2. 



Fig. 61. — Section along a small portion of one of the large posterior nerves 

 in a young female. Externally is seen a distinct connective-tissue coat, and 

 amongst the nerve-fibres are numerous darkly staining elongate nuclei. Zeiss, 

 F, oc. 4. 



Fig. 62. — Diagrammatic representation of the portion of the male repro- 

 ductive organs where the cirrus bulb, dilator rod-sac, and cirrus-sac are in 

 union with one another. Part of the outer wall of the rod-sac and cirrus-sac 

 and the tube running down from these to the atrium genitale has been cut 

 away so as to show the internal structures. The cirrus bulb fuses with the 

 inner side of the muscular mass in the rod-sac. This muscular mass is 

 covered with a thick chitinous layer, and at its apex and on the outer side 

 (that is left of the drawing) is a depression containing a little tongue-like 

 process {To.). On the inner (that is right side of the drawing) the chitinous 

 lining is produced downwards into the somewhat flattened dilator rod (Z>. R.), 

 and passing from this towards the cirrus bulb the surface of the muscular 

 mass becomes deeply grooved, and in this groove the cirrus itself (C) passes 

 outwards from the bulb. In the fully developed form the cirrus almost, but 

 not quite, always passes into the cirrus-sac, where it lies coiled up at rest 

 with its free end pointing towards the atrium genitale. 



Fig. 62a. — Diagrammatic section through the same parts of the female 

 organs as are represented in solid view in Fig. 62, with the exception that in 

 this drawing the cirrus and cirrus-sac are shown complete. The cuticle is 

 represented by the thick dark line. 



Fig. 63. — Transverse section across the cirrus bulb of a not quite mature 

 male. Most internally lies the space continuous backwards with that of the 

 vas deferens, and forwards with that of the cirrus. The chitinous lining is 

 directly continuous with the wall of the latter. The three layers forming the 

 wall of the bulb are indicated bv letters E^, Ej, £",. Zeiss, apo., i'O mm., 

 apert. 0"95, oc. 4. 

 Fig. 64. — Transverse section across the dilator rod-sac where the cirrus 



