THE ANATOMY OF PENTASTOMUM TERETIUSCULUM. 63 



concerned with the rod is cut through. The cirrus-sac on either side is cut 

 through behind its union with the rod-sac, and within it are seen sections of 

 the cirrus. The muscles concerned in pulling downwards the genital sacs 

 are cut through at the base of the rod-sacs. The hook-glands are distinct. 

 Outline drawn with camera, Zeiss, A*, details, C, oc. 2. 



Fig. 15 (cf. Section D). — The transverse section across the body of a male 

 through the plane D. The section is slightly oblique, the right side lying a 

 little behind the left side. On the latter just the very end of the rod-sac is 

 cut through, and the cirrus bulb. On the right side the termination of the 

 vas deferens is cut through, and on each side lies a section through the 

 posterior portion of the cirrus-sac. The two posterior nerves lie on the 

 ventral side, each being supported by a distinct mesentery connected with 

 the oblique muscles. Outline drawn with camera, Zeiss, A*, details with 

 C, oc. 2. 



PLATE IV. 



List of References. 



C. S. Cirrus-sac. Coag. Coagulum in body-cavity. Cu. External cuticle. 

 E. Subcuticular epithelium. Ej.D. Ejaculatory organ. ZT/t. ^/. Hook-gland. 

 Jlk.gl^. Portion of hook-gland lying internal to the vas deferens. Hk. gl^. 

 Portion of hook-gland lying external to the vas deferens. L. Lateral line. 

 L. S. Lateral division of body-cavity. 3f. Long. Longitudinal muscles. 

 M. Tr. Transverse muscles. Mes. Dorsal mesentery supporting the testis in 

 the male, and the ovary in the female. Mes.y Mesentery passing from 

 alimentary canal to the hook-gland and from the latter to the body-wall. 

 Mes^. Mesentery supporting ventral nerve. 0. M. Oblique muscles. Od. 

 Oviduct. Ov. Ovary. Pa.gl. Parietal glands. R.S. Receptaculum seminis. 

 T. Testis. U. Uterus. V. D. Vas deferens. V. S. Vesicula seminalis. 

 V. S. 0. Opening of V. S. into testis. 9. Ventral nerve. 



EiG. 16 (cf. Section E). — Transverse section across the body of a male 

 through the plane E. The very posterior end of the cirrus-sac is cut through 

 on either side, and on the left, which lies slightly in front of the right side, 

 the full width of the vas deferens is cut through. On the right the ejacu- 

 latory duct is seen connected with the ventral side of the vas deferens. In 

 the mid -dorsal line the common portion of the two vesiculae seminales is cut 

 through, though contraction of the walls has obliterated the space. This 

 part is supported by two mesenteries. Each vesicula in reality passes through 

 the hook-gland of its side, though in the adult only remnants of the portion 

 lying to the outer side can be detected (Hk. gl.„), the inner portion being 

 much reduced in size. Outline drawn with camera, Zeiss, A*, details with 

 C, oc. 3. 



Fig. 17 (cf. Section F). — Transverse section across the body of a male 



