THE ANATOMY OP PENTASTOMUM TERETIUSCULUM. 65 



female. The ovary has the normal form, but no shells are yet developed 

 around the eggs. The uterus contains thread-like structures, vrhich may 

 possibly be masses of spermatozoa on tlieir way inwards, but not a trace of 

 any are to be found in the ovarian tube. The body-cavity is largely lined 

 by a cellular material, which also forms the mesenteries. Parietal gland- 

 cells are well developed. Outline drawn with camera, Zeiss, A*, details with 

 C, oc. 2. 



PLATE V. 



List of References. 



A. Supra-oesophageal nerve commissure. Ace. Male accessory organ. 

 Ant. Anterior half of annulus. Ai. gen. Atrium genitale. B. Hk. Basal joint 

 of hook. Co. Tube leading to atrium genitale. Cu. External cuticle. 



B. R. Dilator rod. D. R. S. Dilator rod-sac. E. Subcuticular epithelium. 

 Ej. D. Ejaculatory organ. Gl. ? Gland of unknown function. Hd. gl. Head- 

 gland. Hk. Hook. Hk. gl. Hook-gland. Rk. gl. d. Ducts from hook-gland. 

 Bk. m. Muscles of hooks. L. S. Lateral portion of coelom. M-^. Muscles from 

 cirrus bulb to body-walls behind male opening, i/o. Muscles around accessory 

 male organ. M^. Muscle-band from dorsal body-wall to anterior wall of atrium 

 genitale. M^. Circular muscles around tubes leading to atrium genitale. M. 0. 

 Mid-gut. M. Long. Longitudinal muscles. M. Tr. Transverse muscles. Ng. 

 Central nerve mass. Nu. Nuclei between muscle fibres. (Zi. (Esophagus. Od. 

 Oviduct. 0. M. Oblique muscles. Pa. gl. Parietal glands. Post. Posterior 

 half of annulus. R. Ridge on annulus. S. 0. Sense-organ on papilla. St.gl. 

 Opening of stigmatic gland. F. D. Vas deferens. V. S. Vesicula seminalis. 

 1. Nerve to anterior wall of oesophagus. 3. Nerve to sense-organ. 



Fig. 24. — Longitudinal vertical section through the anterior part of the 

 body of a small young female. The section lies to one side of the median 

 line, and passes through the hook-gland, showing the fusion of the hook, 

 head, and parietal glands at the anterior end of the first-named. The longi- 

 tudinal muscles are seen to run dorsally along the head region, whilst the 

 transverse ones stop short close to where the head unites with the trunk {x). 

 The head space is largely occupied with hook muscles. The oviduct runs 

 through the hook-gland, passing as it does so close to the gland-ducts. Zeiss, 



C, oc. 2. 



EiG. 25. — Longitudinal vertical section through the anterior end of the 

 body of a male form. The section is cut to one side of the middle line, and 

 passes through the dilator rod-sac and the accessory gland. The latter runs 

 upwards into the hook-gland, and is surrounded by special muscles which are 

 connected with the strongly developed layer surrounding the sac. Zeiss, 

 C, oc. 2. 



VOL. XXXIV, PART I. — NEW SER. S; 



