UNIVERSITY OF CAPE TOWN. Zoological Department. DISSECTION OF The Platana and the Frog BY J. D. F. GILCHRIST, M.A., D.SC., PH.D., _Professor of Zoology in the University of Cape Town_, AND C. VON BONDE, M.A., _Lecturer in Zoology in the University of Cape Town_. [Illustration] 1919. CAPE TIMES LIMITED, CAPE TOWN. PREFACE AND INSTRUCTIONS. Owing to the fact that some of the types of animals available for the study of Zoology in South Africa differ from those described in text books for students in other countries, it has been found necessary to draw up special directions and diagrams for laboratory use in this country. These are now put in the more convenient form of a text book, which, though intended primarily for the use of the students of the University of Cape Town, may, it is hoped, prove useful to others engaged in the teaching and study of Zoology in South Africa. The general plan of the course intended to be followed is first an introductory study of a type of vertebrate. The Platana or Clawed Toad, _Xenopus lævis_, is the most convenient type for this in South Africa and in some respects is more instructive than the Frog. Xenopus is therefore chiefly dealt with, but Rana can also be used, the differences in this type being indicated in italics. It is recommended that both types be studied where possible. Only these two types are dealt with here, but may be followed by descriptions of other South African types, such as the South African Crawfish, Dogfish, Earthworm, etc. It is intended that the student should make drawings of his dissections on the blank page. He should not copy the diagrams, but draw what he actually sees, and be prepared to demonstrate the parts to the teacher. The instruments required are a large and a small pair of scissors, a large and a small scalpel, moderately fine forceps, a seeker, and pins. We are indebted to Mr. W. von Bonde, M.A., for the drawing of Figs. 3-5, 7-10. J. D. F. G. C. v. B. _Zoological Laboratory, University of Cape Town, June, 1919._ THE PLATANA (_Xenopus lævis_). THE FROG (_Rana fuscigula_). _First Day._ External Characters. 1. Make a drawing of the animal viewed from above, showing:-- (_a_) The nostrils. (_b_) The eyes. (_c_) The nictitating membrane and a short tentacle beneath the eye. [_The tentacle is absent in the Frog._] (_d_) The tympanic membrane, which is not shown in the Platana, but is well marked in the Frog. (_e_) The opening of the cloaca. (_f_) The limbs and their divisions. (_g_) The skin with tube-like lines round the body. [_In the Frog these lines are not present._] [Illustration: FIG. 1.--Xenopus lævis and Rana fuscigula.] 2. Make an enlarged drawing, about twice the natural size, showing:-- (_a_) The fore-limb with the digits. (_b_) The hind-limb with the digits. The inner three digits have claws. [_The claws are absent in the Frog._]