208 ON AK HTDEAOHNID fOCND IN OOBNWALL. [Mar. 5, 



Fig. 18. The penial canal, ductus ejaculatorius, and vasa deferentia seen from 

 the side, X 190. 



Pig. 19. Section through one of the so-called genital suckers and a portion of 

 . the adjoining cuticle, X •'580. 



Fig. 20. The great central nervous ganglion (the so-called brain), X 175, 

 showing the various nerves proceeding from it, and the CESophagus 

 passing through it. The entire length of one of the optic and one of 

 the palpal uerves is shown, the other nerves are cut short. 



Fig. 21. The respiratory organs on one side of the body, X 280, showing the 

 sigmoid piece (sp.) with the air-chamber inside, and the connection of 

 the sigmoid piece with the mandible. The tracheal trunk proceeding 

 to the stigma {tra.) is shown, as is also a small portion of the efferent 

 tracheal trunk (tre.). The distal (anterior) portion of the common 

 duct from the salivary glands is seen behind the muscles, and one 

 band of muscle is partly cut away to show the two ducts from the 

 quadrate gland joining the common duct. 



Fig. 22. One of the palpal organs, X 175. The figure does not include quite 

 the whole of the anterior end of the organ, which extends nearly to 

 the distal end of the palpus. The first joint of the palpus and a 

 portion of the second are shown in section. 



Platb IX. 



8ectio7is. 



[All the figures in this Plate are drawn from preparations fixed with picro- 

 siilphuric acid and stained with hsematoxylin.] 



Fig. 23. Sagittal median section of (^, X 120. It is a thick section so as to 

 show organs which are not quite in the actual median plane if there 

 be not anything in that plane to hide them. 



The chitinous plates m the cuticle (cp.) are left white, all those in 

 this section are the larger areolated kind of plate, none of the smaller 

 perforated hair-bearing plates come into the median section. Only 

 one dermal gland {dg^ is seen at the anterior end ; the section just 

 catches the exterior tunic of this gland, so that it is not really a section 

 of the gland but an exterior view ; sections of these glands are seen in 

 figs. 24, 25. The azygous salivary gland {sa.) and one of the quad- 

 rate salivary glands are seen, but neither the reniform nor the 

 tubular salivary glands come into the median section. The oeso- 

 phagus («.) is seen passing through the brain {br.). The anterior 

 median portion of the ventriculus ( V.) and its anterior azygous cfficum 

 are seen, as is also the hind bridge {vb.) of the organ near the posterior 

 end, but the lateral portions wliich join the two and complete the 

 hollow square are not seen. The whole length of the excretory organ 

 {E.) is shown ; it contains excretory matter. The whole length of the 

 pharyngeal nerve {nph.) is shown, and just the commencement of the 

 recurrent nerve at the posterior edge of the sub-cesophageal portion 

 of the brain. A small part of the testicular mass {T.) on one side of 

 the body is seen in consequence of its having, from its large size, 

 extended itself over the median line. The whole lengths of the penial 

 canal (P.) and ductus ejaculatorius {de.) are seen, but not the vasa 

 deferentia. 



Fig. 24. Longitudinal section through a portion of the dorsal cuticle, X 175. 

 The section cuts through some of the larger (areolated) chitinous 

 plates icp.) and shows that the epiostracum {cp.) is gone from above 

 them. The chitin of the plates is left white except in the areolations, 

 which are mostly filled by living protoplasmic tongues from the cells 

 of the hypoderm {H.). Two dermal glands are seen in section, but 

 they have not been cut in the plane which contains the duct ; this 

 does not fall into the same vertical plane as the areolated chitinous 

 plates. 



Fig. 25. Section through one of the anterior dorsal dermal glands, x 175, 



