91 8 EXPLANATION OF PLATES. 



Fig. 15. Section through the point of junction of the salivary ducts with the 

 median oral diverticulum. 



Fig. 1 6. Section behind the pharynx through the oesophagus. 



b. c. Body-cavity, c. Cutis. c. b. c. Central compartment of body-cavity, c. g. 

 Supra-cesophageal ganglia, c. m. Layer of circular muscles, co. Commissure between 

 ventral nerve-cords. co. i. Second commissure between the ventral nerve-cords. 

 co 1 . 2. Mass of cells developed on second commissure (probably sensory), c. s. d. 

 Common duct for the two salivary glands, d. I. m. Dorsal longitudinal muscles of 

 pharynx, d. o. Muscles serving to dilate the opening of the pharynx. Ep. Epider- 

 mis, e. n. Nerve passing outwards from ventral nerve-cord. H. Heart, i.j. Inner 

 jaw. j.p. Jaw papillae. L. Lips of buccal cavity. /. b. c. Lateral compartment of 

 body-cavity, le. Rod-like cuticular continuation of inner jaw, lying in a pit of the 

 buccal cavity. /. m. Bands of longitudinal muscles. M. Buccal cavity. M 1 . Median 

 backward continuation of buccal cavity. m.L Muscles of jaw lever, m. s. Muscular 

 sheets passing from side walls of pharynx to dorsal body wall. ft'. Oesophagus. 

 a's. co. OZsophageal commissures. o.j. Outer jaw. ph. Pharynx. s. d. Salivary 

 duct. s. g. Salivary gland, si. d. Reservoir of slime gland, sy. Sympathetic nerves 

 running in muscles of tongue or pharynx, sy 1 . Origin of sympathetic nerves to 

 pharynx. T. Tongue, v. c. Ventral nerve-cords. 



Figs. 17, 1 8. Two longitudinal horizontal sections through the head of Peripattis 

 capensis. Fig. 17 is the most ventral. They are both taken ventral to the cerebral 

 ganglia. In Fig. 17 dorsal tracheal pits are shewn with tracheae passing off from 

 them. (Zeiss a a, Hartnack's camera.) c. Cutis. c. s. d. Common salivary duct. 

 ep. Epidermis, i.j. Inner jaw. M. Buccal cavity. M 1 . Median backward diverti- 

 culum of mouth, o.j. Outer jaw. s. d. Salivary ducts. T. Tongue. /. Teeth on 

 tongue, tr. Tracheae, tr. p. Tracheal pits. 



PLATE 50. 



Fig. 19. "A, B, c, D, E, F, G. Seven transverse sections illustrating the structure 

 of the supra-oesophageal ganglia. (Zeiss A, Hartnack's camera.) a. Dorso-lateral 

 horn of white matter. b. Ventro-latefral horn of white matter, c. Postero-dorsal 

 lobe of white matter, d. Ventral protuberance of brain, e. Central lobe of white 

 matter, o.p. Optic ganglion. 



" A. Section through anterior portions of ganglia close to the origin of the anten- 

 nary nerve. B. Section a little in front of the point where the two ganglia unite, c. 

 Section close to anterior junction of two ganglia. D. Section through origin of optic 

 nerve on the right side. E. Section shewing origin of the optic nerve on the left side. 

 F. Section through the dorso-median lobe of white matter. G. Section near the termi- 

 nation of the dorsal tongue of ganglion cells." 



PLATE 51. 



Fig. 20. Portion of a transverse section through the hinder part of Peripatm 

 capensis (male). The section passes through a leg, and shews the opening of the 

 segmental organ (o. s.), and of a crural gland, o.f.g., and the forward continuation of 



