OF THE SKULL IN SHARKS AND SKATES. 191 
Axsurt Gintuer. “ Description of the Ceratodus, a Genus of Ganoid Fishes recently discovered 
in Rivers of Queensland, Australia.” Phil. Trans. 1871, part ii. pp. 511-571, pl. 30-42. 
Cart Grcrenpavr. ‘ Untersuchungen zur Vergleichenden Anatomie der Wirbelthiere’ (part 3. 
Selachians). Leipzig, 1872. 
Then follow in natural order, the writer's own papers in the ‘ Philosophical Trans- 
actions’ on the structure and development of the skull in various types. The present 
paper is one of the same kind, but especially intermediate between M. Gegenbaur’s 
splendid work and the invaluable researches now to be noticed. 
F. M. Batrour— 
1. “A Preliminary Account of the Development of the Elasmobranch Fishes.’ 
Mier. Se. Oct. 1874. 
. “The Development of Elasmobranch Fishes.” Journ. of Anat. & Phys. vol. x. pp. 517-570, 
pl. 21-26. 
3. “The Development of Elasmobranch Fishes.” Ibid. pp. 677-688, pl. 29. 
? Quart. Journ. of 
~ 
ibe 
. ‘A Comparison of the Early Stages in the Development of Vertebrates: Studies from the Phy- 
siological Laboratory in the University of Cambridge.’ Part ii. 1876, pp. 1-20, pl. 1. 
Although out of order, I must mention two important papers recently sent me by 
the author. 
Burt G. WitpEr. 
1. “ Notes on the North-American Ganoids Amia, Lepidosteus, Acipenser, and Polyodon.” Proc. 
Am. Assoc. for Adv. of Se.: Detroit Meeting, Aug. 1875. Salem, Mass., 1876, pp. 151-194, 
pl. 1-3. 
2. “ Note on the Development and Homologies of the Anterior Brain-mass of Sharks and Skates.” 
Am. Journ. of Se. & Arts, vol. xii. Aug. 18761. 
I mention these last papers because of the necessity of studying the nervous and 
skeletal systems together, and also because of the intimate relation of the Selachians 
with the Ganoids. 
In the following description allusion will be made to the condition of the stages of 
the skull in other types, especially in the Ichthyopsida. 
But the intimate relation of the skull of the Amphibia with that of the Selachians 
is best seen in the outlying forms of the latter group, namely Cestracion, Notidanus 
(Heptanchus, and Hexanchus), as these come nearest to the Chimeroids on one hand, 
and to the larval Batrachia and Urodela on the other. 
Professor Huxley’s paper on Menobranchus, a Perennibranchiate Urodele, has been 
of the utmost service to me; and by the time the present communication is published, 
I hope to have also in print my second paper on the Batrachian skull, and my first on 
that of the Urodeles. These, in addition to remarks on the growth and changes of the 
1 Several fresh papers by my friends Balfour and Wilder have reached me since the above list was written. 
2u 2 
