THE ANATOMY OF PENTASTOMUM TEBETITJSCULUM. 69 



ovary has the form of a tube, the walls of which are flattened from above 

 downwards, and the space is continued into little pouch -like lateral diver- 

 ticula, through two of which the section passes. The upper wall of the main 

 tube is syncytial in nature ; the lower wall is composed of columnar cells. 

 The tube is surrounded by eggs of various sizes, each enclosed in a definite 

 shell. There is no enclosing membrane, and the mesentery arises from the 

 mid-dorsal surface. Zeiss, F, oc. 4. 



Fig. 44. — Transverse section across the ovary of an immature female. 

 The upper and lower walls of the tube are distinct as in the mature state, but 

 the lower one is composed of more distinctly nucleate columnar cells. There 

 is no surrounding mass of eggs enclosed in shells, but groups of ova form the 

 walls of the lateral diverticula, only one of which is cut through. The mesen- 

 tery is cellular in nature. Zeiss, C, oc. 4. 



Fig. 45. — Transverse section across the commencement of the vagina. 

 Externally is seen the thick muscular coat, then the layer of columnar epithe- 

 lium, and internal to this a mass showing radial markings (a:.), and lined 

 internally by a thin cuticular layer thrown into little ridges and points. A 

 few special gland-cells are enclosed in connective tissue externally to the 

 muscles. Zeiss, E, oc. 2. 



Fig. 46. — Transverse section across the ejaculatory duct of a mature male 

 form. Externally the layer of very strong muscle slips is cut in section, 

 within this the membrana propria, and within this the layer of columnar epi- 

 thelium with its chitinous lining, the latter thrown into fine ridges and pro- 

 jecting points. Zeiss, F, oc. 2. 



Fig. 47. — Transverse section across the part of the reproductive organs of 

 a mature male where the vesicula seminalis joins the vas deferens. The well- 

 marked layer of glandular cells surrounding the latter is seen, and the duct 

 lined by chitin. The walls of the vesicula have been much distended, and are 

 thin. Zeiss, F, oc. 4. 



Fig. 48. — Section across the wall of the cirrus-sac of a mature male. 

 Externally is a strong muscle layer, and within this, the deep columnar epi- 

 thelium with its well-marked cuticular lining. Zeiss, apo., 4*0 mm., 0'95 

 apert., oc. 8. 



Fig. 49. — Section through the primary papilla of a young female to show 

 the relationship of the sense-organ and the opening of the hook-gland. The 

 sense-organ is composed of columnar cells, some of which are nucleated. A 

 large nerve with nuclei amongst the fibres enters the inner side of the organ, 

 which has no definite outline. At its opening the hook-gland is surrounded 

 by a layer, sometimes more than one cell thick, of cubical nucleate cells, and 

 the external chitinous layer is directly continuous with that lining the duct. 

 Zeiss, F, oc. 4. 



