Z. Malleus, Valenc. in Mem. du Mus. (1822). torn. ix. p. 223. pl. 11. f. 1.? Cuv. Reg. An. torn. 11. p. 393. Squalus Zygsena, Linn. Syst. Nat. torn. 1. p. 399.

A fish of this genus is recorded by Messrs. C. and J. Paget * as having occurred at Yarmouth, October 1829. The head is said to be preserved in the Norwich Museum. As, however, the species have been much confounded, and the exact one in this instance does not appear to have been determined, it is impossible to annex any description. The Squalus Zygcena of Linnaeus is the Z. Malleus of M. Valenciennes, who has published detailed descriptions of four species of this genus, accompanied in each case by a representation of the head, which appears to offer the best characteristic marks for distinguishing them. In the Z. Malleus, which is the most common species, the head is in the form of a very long rectangle; the anterior margin straight, and deeply notched near the external angle; the nostrils immediately beneath the notch. The Squalus Zygcena of Bloch is a distinct species, in which the nostrils are removed much further from the eyes. M. Valenciennes' memoir, which is referred to above, should be consulted by those who may have an opportunity of seeing any other British specimen of this genus.