60 W. BALDWIN SPENCER. 



EXPLANATION OF PLATES I— IX, 



Illustrating Professor Spencer's paper on '' The Anatomy of 

 Pentastomum teretiusculum." 



PLATE I. 



Fig. 1. — Ventral view of a female Pentastomum teretiusculum. x 2. 



Fig. 2. — Ventral view of the anterior end of the body of a female, to show 

 the mouth and the arrangement of the hooks and sensory papillaj. 1. Paired 

 primary papillae. 2, 6, 7, and 8. Paired secondary papillae. The division of 

 the annuli into anterior and posterior halves by a distinct ridge is repre- 

 sented. X 12. 



Fig. 3.— Dorsal view of the anterior end of the body of a female, to show 

 the sensory papillae. Only the outer pair of hooks are seen. 1. Paired 

 primary papillae. 2, 3, 4, and 5. Paired secondary papillae. X 12. 



Fig. 4. — Ventral view of a male Pentastomum teretiusculum. x 4. 



Fig. 5. — Ventral view of the anterior end of the body of a male, to show 

 the mouth, atrium genitale, arrangement of the hooks and sensory papillae. 

 1. Paired primary papillae. 2, 7, 8, and 9. Paired secondary papillae. 



PLATE II. 



List of References. 



A. Supra-oesophageal commissure, a. Duct to primary papilla, b. and c. 

 Ducts to bases of hooks. Ace. Accessory organ, male. Ace. F. Accessory 

 organ, female. AL gen. Atrium genitale. C. B. Cirrus-bulb. Co. Tube 

 leading to atrium genitale. C S. Cirrus-sac. B. R. S. Dilator rod-sac. 

 Ej. D. Ejaculatory organ. Hd. gl. Head-gland. Hk. Gl. Hook-gland. L. 

 Lateral line. L. S. Lateral division of body-cavity. M.^ Muscles around 

 male accessory organ. M. Long. Longitudinal muscles. M. Tr. Circular 

 muscles. Mes. Median-dorsal mesentery, supporting testis in male and ovary 

 in female. Mes.^. Lateral mesentery from hook-gland to alimentary canal, and 

 from hook -gland to body -wall. Mes^. Mesentery to ventral nerves. N. 

 Central nerve mass. 0. M. Oblique muscles. Od. Oviduct. Ov. Ovary. 

 Pa. gl. Parietal gland-cells. Sp. Spermatheca. Sp. D. Duct of spermatheca. 

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



Fig. 6. — Diagrammatic representation of the alimentary, secretory, nervous, 

 and reproductive systems of a male Pentastomum teretiusculum, seen 

 from the side. For the sake of simplicity the parietal glands have been 

 omitted, and only the portion of the head-glaud where it unites with the 



