THE ANATOMY OF PENTASTOMUM TEEBTIUSOULUM. 61 



hook-gland is sliown. The different structures are named, a. Duet from 

 hook- and head-glands to primary papillae, b and c. Ducts from hook- and 

 head-glands to hooks. 1. Nerve to anterior wall of fore-gut. 2. Nerve to 

 posterior wall of fore-gut. 3. Nerve to sensory papillae. 4. Nerve to 

 muscles, &c., at side of body. 5. Nerve to hooks. 6. Nerve to mid-gut. 

 7. Nerve to hook-gland. 9. Ventral nerve. A. (Esophageal commissure. 

 The lines indicated by the capital letters A, B, C, D, E, F, G, H, and I indi- 

 cate the planes of the sections correspondingly lettered. 



Fig. 7. — Diagrammatic representation of the alimentary, secretory, nervous, 

 and reproductive systems of a female Pentastomum teretiusculum, 

 seen from the side. The alimentary, secretory, and nervous systems as in 

 Fig. 6. The lines indicated by the capital letters K and L indicate the planes 

 of the sections correspondingly lettered. 



Fig, 8. — Semi-diagrammatic representation of the reproductive organs of a 

 male Pentastomum teretiusculum, seen from the dorsal surface. The 

 lines indicated by the capital letters correspond to those in Fig. 6. 



Figs. 0, 7, and 8 are constructed as the result of examination of dissec- 

 tions, and of series of consecutive sections. 

 Figs. A, B, C, D, E, F, G, H, and I represent diagrammatic transverse 

 sections across the body of a male Pentastomum teretiusculum, 

 along the lines indicated by corresponding letters in Figs. 6 and 8. 

 The three muscle layers of the body are represented by thick lines, 

 but in all cases the parietal gland-cells and subcuticular layer are 

 omitted for the sake of clearness. 

 I'igs. K and L represent diagrammatic transverse sections across the 

 body of a female Pentastomum teretiusculum, along the lines 

 indicated by corresponding letters in Fig. 7. 



PLATE III. 



List of References. 



a. Extensor muscle of the hook. Ace. Male accessory organ. At. gen. 

 Atrium genitale. b. Flexor muscle of the hook. C. Cirrus. C. B. Cirrus 

 bulb. C. S. Cirrus-sac. Co. Tube leading down on each side to the atrium 

 genitale. Cu. External cuticle. D. R. Dilator rod. D. R. S. Dilator rod- 

 sac. Gl. ? Gland of unknown function. Ed. gl. Head-gland. Hk. Hook. 

 Hk. d. Ducts to hooks. Hk. gl. Hook-gland. Hk. gl. d. Ducts to primary 

 papillae. Hk. i. Invagination in which base of hook lies. Hk. m. Hook 

 muscles. L. Lateral line. L. S. Lateral division of body-cavity. 31^. 

 Muscles connected with dilator rod-sac. M„. Muscles surrounding male 

 accessory organ. M^. Circular muscles round tubes leading to atrium genitale. 

 Mes.^. Mesentery to ventral nerves. M. G. Mid-gut. M. Long. Longitudinal 

 muscles. M. Tr. Circular muscles. N. Central nerve mass. 0. Hk. Gl. 



