Quarterly Journal of Microscopical Science, Vol s2-80, 99-125, Copyright © 1937 by Company of Biologists

Memoirs: The Reproductive System of the Planarian Artioposthia Triangulata (Dendy)

¹ Lecturer in Zoology, University of Otago, New Zealand

The main subject of this paper is a detailed description of the reproductive organs of a planarian initially described by Dendy as Geoplana triangulata. Five unusual features are observed in the reproductive system:

1. The vas deferens consists of a series of wide convoluted branching tubes extending from the region of the mouth to the anterior end of the seminal vesicle.

2. The penis is very small and inconspicuous.

3. The atrium masculinum is provided with three pairs of muscular gland-organs or adenodactyli.

4. The paired ovaries are situated one on each side of the seminal vesicle, not in the region of the brain as is usual.

5. Each ovary is a long fusiform body enclosing more than one true ovary or germarium, as well as specialized parovarian and amoeboid cells which are probably nutritive, and are associated with the internal opening of the oviduct.

The writer refers Geoplana triangulata Dendy to the genus Artioposthia owing to the presence of adenodactyli in the atrium masculinum. Each adenodactylus encloses a glandular reservoir from which a ciliated duct leads to the atrial cavity. The actual function of the adenodactyli is obscure, but the very small size of the penis and the fact that the adenodactyli are extrusible suggests the possibility of these latter performing the function of a penis.