(4) the germinal epithelium lining the body-cavity.
[192] Unless the contrary is stated, the facts recorded in this chapter apply only to the genera Scyllium and Pristiurus.
[193] The layers are known as epidermic (horny) and mucous layers by English writers, and as Hornschicht and Schleimschicht by the Germans. For their existence in all Vertebrates, vide Leydig Ueber allgemeine Bedeckungen der Amphibien, p. 20. Bonn, 1876.
[194] Vide Leydig, loc. cit.
[195] Vide Götte, Entwicklungsgeschichte der Unke.
[196] Vide Self, “Development of Spinal Nerves in Elasmobranchii.” Phil. Trans. 1876. [This Edition, No. VIII.]
[197] For Birds, vide Elements of Embryology, Foster and Balfour, pp. 144, 145, and for Mammals, Kölliker, Entwicklungsgeschichte, p. 283.
[198] For the nervous supply in fishes, vide Stannius, Peripher. Nerv. System d. Fische. In Osseous Fishes he states that the thoracic fin is supplied by branches from the first three though sometimes from the first four spinal nerves. In Acipenser there are branches from the first six nerves. In Spinax the limb is supplied by the rami anteriores of the fourth and succeeding ten spinal nerves. In the Rays not only do the sixteen anterior spinal nerves unite to supply the fin, but in all there are rami anteriores from thirty spinal nerves which pass to the thoracic limb.
[199] Philosophical Transactions, 1871.
[200] Ursprung d. Wirbelthiere and Functionswechsels.