8 
W. F. R. WELDON. 
EXPLANATION OF PLATE I, 
Illustrating Mr. Weldon’s paper ou “Haplodiscus piger.” 
List of Reference Letters. 
Al. Alimentary mass. Br. Brain. Cu. Cuticle. I). E. Ductus ejacula- 
torius. F. Food particle in food vacuole, fo. Follicle cells of ovary. Gl. 
Gland-cell. i. cu. Inner layer of ventral cuticle, m. 1. Lougitudiual muscles. 
m. 1. ep. Epithelial portion of muscle-fibres, m. t. Transverse muscles. M. 
Mouth. Oo. Ovary. P. r. Protoplasmic reticulum. Sp. Sensory processes 
in connection with brain. Te. Testis. V. S. Vesicula seminalis. Y. Yellow 
cells. 
Fig. 1. — View of Haplodiscus piger, under a simple lens, (x about 
40 diam.) 
Fig. 2. — Transverse section through the middle of the body, showing the 
relations of the mouth and alimentary system, the ovaries, and the testis. 
Fig. 3. — Transverse section through the anterior end of the body, showing 
the brain. 
Fig. 4. — Small portion of longitudinal section of the ventral surface, show- 
ing the structure of the body wall. 
Fig. 5. — From a longitudinal section which cut tangentially the sheath of 
the ductus ejaculatorius, showing the transition between the muscles of 
the sheath of that organ and those of the body wall. 
Fig. 6. — Small portion of a horizontal section through the peripheral proto- 
plasmic tunic, showing the absence of cell-outlines, and the relations of the 
glands and yellow cells. 
Fig. 7. — Two muscle-fibres, from the neighbourhood of the ductus ejacu- 
latorius. 
Fig. 8,«. — Young sperm-cells from the testis, lying in the general reticulum. 
Fig. 8,6. — A sperm-morula from the testis. 
Fig. 8, c .~ Ripe spermatozoa. 
Fig. 9. — Ovum observed in one specimen, with nuclear spindle and perhaps 
a polar body. 
Fig. 10. — Diagram of median longitudinal section. For the sake of clear- 
ness the yellow cells are omitted. 
