a. Brain. b. Last ganglion. Between these will be observed the chain of ganglia of which they form portions. c. Lateral or branchial vessels. d. Folded mucous glands; each is connected by a duct to an air-vesicle. e. Penis, the rounded enlarged base of which is supposed to contain the prostate gland. f. Vesiculae seminales. g. Vasa deferentia. h. Testicles. i. Uterus. k. Ovaries.

This image is from _ in Pereira's Elements of Materia Medica and Therapeutics, 1854.