178 W. B. BENHAM. 



the pharynx, opening by a wide mouth, sept. One of Uie septa : the first 

 one appears to be between Somites ii and lii. The relative thicknesses of 

 epitheliam in various parts are repreaented. The letters a, b, c, d, merely 

 indicate points or regions to be compared with those similarly lettered in 

 Fig. 13. 



Fig. 13.— a longitudinal section through the anterior end of a specimen in 

 which the buccal cavity is everted. The series of sections were not quite 

 parallel to the vertical plane, so that the upper portions are really more 

 laterally situated than the lower ; hence the sac of the pharynx appears to 

 open by a narrow orifice: this is merely the narrower lateral part of the orifice, 

 which is wider medially. Most of the letterings as in Fig. 12. sal. gl. 

 Salivary gland, ces. (Esophagus. long. The longitudinal muscles of the 

 body-wall. circ. The circular muscles, a, b, c, d, indicate regions for com- 

 parison with their position in Fig. 12. 



Fig, 14. — A portion of the epithelium at a in Figs. 12 and 13. 



Fig. 15. — A portion of the epithelium of the buccal cavity between b — c 

 in Fig. 12. 



Fig. 16. — A portion of the epithelium from the floor of the pharynx 

 behind c in Fig. 12. 



Fig. ] 7. — A portion of the epithelium of the roof of the sac of the pharynx 

 behind d in Fig. 12. 



Fig. 18. — A portion of the wall of the intestine where the septum {sept.) 

 nips it, as at a in Fig. 7. Int. epith. Intestinal epithelium, the details in which 

 are represented only on the left. Each cell has a dense, deeply staining 

 border, represented in the figure by the darker line; and the light band out- 

 side this is probably caused by closely pressed cilia, circ. mus., Ig. m. The 

 muscular coats of the intestine. The blood-clot in the perienteric blood- 

 sinus exhibits a peculiar fringing of its outer border. 



Fig. 19. — The ventral half of a transverse section through Somite xvi, 

 in order to show the epidermic position of the sperm-duct on each 

 side — immediately outside the tubercula pubertatis {tub. pub.). vent. ch. 

 Ventral chsetaj. cl. Clilellum. cl'. The thin extension of the clitellum across 

 the ventral surface. 



Fig. 20. — A portion of a transverse section more highly magnified, showing 

 the structure of the sperm-duct. The specimen of which this is a section had 

 passed its sexual maturity. The epidermis {ep.) is evident, the rounded nuclei 

 indicating rather short cells whose outlines are not evident. Eelow is a 

 peculiar tissue — due, I believe, to degenerate clitellar cells {cl. deg.). b. v. 

 Blood-vessels in this region, circ. Circular muscles, long. Longitudinal 

 muscles. 



Fig. 21. — A portion of a transverse section in the same series as that of 



