STUDIES ON THE TURBELLARIA. 465 
d. Ducts leading to chitinous mouth-pieces. d@’. Enlargements of duets of 
mouth-pieces. e¢. Eye. et. Enteric cavity. ep. Epidermis. ez. Main ex- 
cretory vessels. f.%. Frontal nerves. g.d. Ducts of granule glands. gl. 
Unicellular glands opening into antrum. g.7. Granule reservoir. ¢. Intes- 
tine. #&. Supposed passage by which the eggs are discharged. /. m. Longi- 
tudinal muscular fibres of body-wall. 7.2. Lateral nerve. mth. Mouth. 
n. Nucleus. od. Oviduct. oo. Oosperm. of. Cavity in which otocyst lies. 
ov. Ovary. p. Penis. ph. Pharynx. pl. Polar body. pr. Processes con- 
necting epidermal cells. p.s. Penis sheath. r#. Rhabdite-forming or other 
integumentary glands. ri. d. Ducts of integumentary glands. 1. s. Recepta- 
culum seminis.’ sh. Egg-membrane. ¢. Testis. w. Uterus. v. Vesicula 
seminalis. 2. Position of supposed Laurer’s canal. z. Group of cells behind 
‘brain. @. Male reproductive aperture. 9. Female reproductive aperture. 
PLATE 25. 
Fie. 1.—Outline of Heter ocherus magnified 20 times to show the relative 
positions of the mouth and reproductive apertures. 
Fie. 2.—Semidiagrammatic view of the general organisation. xX 40. 
Fic. 3.—Transverse section through the epidermis and underlying layers. 
x 1500. 
Fic. 4.—Pigment cell of epidermis. X 1675. 
Fic. 5.—Rhabdites. x 1500. 
Fie. 6.—Symbiotie Zoochiorella. x 600. 
Fic. 7.—Portion of a horizontal section passing through the digestive syn- 
cytium, showing large numbers of the Alge in the more superficial layers of 
the latter. Facsimile of a photograph. 
Fie. §.—Portion of a transverse section passing through the mouth. 
Fie. 9.—Horizontal section passing through the so-called pharynx and the 
main enteric cavity. Facsimile of photograph. 
Fie. 10.—Horizontal section on a higher (more dorsally situated) plane 
than that represented in Fig. 8, showing the enteric cavity and the digestive 
plasmodium, with portions of the testes at the sides. Facsimile of photo- 
graph. 
Fie. 11.—Central part of a similar section more highly magnified. The 
black dots are the nuclei of the plasmodium. 
Fie. 12.—Anterior part of a horizontal section passing through the brain, 
the eyes, and the cavity in which the otocyst is enclosed. Facsimile of 
photograph. 
voL. 49, PART 3.—NEW SERIES. 34 
