280 ERNEST W. MACBRIDE. 
in which he has described a pronephros. Marsipobranchs 
have no oviducts. lLepidosteus is the only Tectibranch in 
which anything is known of the development of the generative 
duct, and in it Balfour found reason to believe that the oviduct 
was formed by a prolongation of the same fold which enclosed 
the cavity of the ovary, whilst in Amphibians and Crocodiles 
we have already seen that the pronephros is quite independent 
of the duct. So that we are at any rate justified in saying 
that whatever the oviduct may be, it has nothing to do with 
the pronephros. 
If one might be allowed to found phylogenetic conclusions 
on the facts above related, I would be inclined to say that in 
the phyla of Ganoids, Amphibia, and Reptiles, which groups 
probably approximately represent stages in the actual line of 
descent of Vertebrates, the oviduct is derived from a dorsal 
groove in the peritoneum, just as the portion of it extending 
round the base of the lung is shown to be by actual develop- 
ment in Amphibia. 
I have, in conclusion, to express my warmest thanks to Mr, 
Sedgwick for his advice and assistance through the whole 
course of my work. 
EXPLANATION OF PLATES XII and XIII. 
Illustrating Mr. Ernest W. MacBride’s paper on “The 
Development of the Oviduct in the Frog.” 
List of Reference Letters. 
Br. Brain. ©. Muse. Circular muscles of the cloaca. C.p.e, Columnar 
peritoneal epithelium. /. p. e. Flat peritoneal epithelium. g/. Glomerulus. 
In. Integument. XK. Kidney. K.¢. Kidney tubule. Z. Lung. Liv. Liver. 
L. Musc. Longitudinal muscle of cloaca, /¢. Quasi-embryonic tissue of 
degenerate pronephros, and frout part of mesonephros. Jy. Lymph space. 
M. Cutendof mesentery. Md. oviduct. m/. Oviducal funnel. ch. Noto- 
chord. «@. Gsophagus. Ov. Ovary. pz. f. Pronephric funnel. px. ¢. Pro- 
nephric tubule. 2. Cloaca. Sp. ch. Spinal cord. V. gy. Ventral groove 
