[509] The homologies of the olfactory lobes throughout the group of Fishes require further investigation.
[510] “Ueb. d. Gehirn des Störs,” Müller's Archiv, 1843, and Lehrbuch d. vergl. Anat. d. Wirbelthiere. Cattie, Archives de Biologie, Vol. III. 1882, has recently described in Acipenser sturio a vesicle on the roof of the thalamencephalon, whose cavity is continuous with the third ventricle. This vesicle is clearly homologous with that in Lepidosteus. (June 28, 1882.)
[511] R. Wiedersheim, Morphol. Studien, 1880, p. 71.
[512] “On Ceratodus Forsteri,” &c., Proc. Zool. Soc. 1876.
[513] In Wilder's figure the walls of the cerebellum are represented as much too thin.
[514] Vide F. M. Balfour, Comparative Embryology, Vol. II. figs. 248 and 250.
[515] Vide F. M. Balfour, Comparative Embryology, Vol. II. pp. 355-6 [the original edition], where it is suggested that this commissure is the homologue of the grey commissure of higher types.
[516] We have not been able to work out the early development of the pituitary body as satisfactorily as we could have wished. In Plate 37, fig. 40, there is shewn an invagination of the oral epithelium to form it; in Plate 37, figs. 41 and 42, it is represented in transverse section in two consecutive sections. Anteriorly it is still connected with the oral epithelium (fig. 41), while posteriorly it is free. It is possible that an earlier stage of it is shewn in Plate 36, fig. 35. Were it not for the evidence in other types of its being derived from the epiblast we should be inclined to regard it as hypoblastic in origin.
[517] Morphol. Studien, III. Jena, 1880.
[518] “On Ceratodus Forsteri,” Proc. Zool. Soc. 1876.