DESCRIPTION OF FISHES. 205 
Family Pycnopontes. 
Periodus Kenigii, Agassiz. (Tab. X. fig. 13.) 
The genus Periodus differs from Pycnodus in having the apex of the tooth 
surrounded by a large furrow ; the figured specimen must have belonged to a 
large fish ; it is similar in size to the original fossil] from Sheppey, in the Collec- 
tion of the Very Rev. Dr. Buckland, published in M. Agassiz’s magnificent 
work. 
Mr. Keele has a fine specimen of Periodus found near Southampton. 
Order CYCLOIDEI, Agassiz. 
Genus Platylemus*. 
This genus is founded upon the dental plates figured in Tab. XII. figs. 11, 
12 & 13. They are of two forms; the one, 12 & 13, symmetrical, the other 
(fig. 11) unsymmetrical and evidently one of a pair of plates, resembling the 
upper pharyngeal dental plates of a Labrus or Scarus in general form ; whilst 
the symmetrical plate answers to the lower symmetrical pharyngeal plate in the 
same fishes. The fossil plates consist of a continuous dentary mass, with a 
smooth and nearly flat enamelled surface, finely punctate ; the depressions indi- 
cating the extremities of the vascular canals of the numerous filamentary verti- 
cal denticles, of which the whole mass is composed. On the attached surface of 
the plate, three ridges converge from the three angles to a central pointed pro- 
cess. The specific name Colei is in honour of the Right Hon. the Earl of En- 
niskillen, who, in an excursion with the author to Bracklesham, obtained a fine 
specimen of this new species of fossil fish. 
Sphyrenodus, Agassiz. 
Sphyrenodus gracilis.—The specimen figured M. Agassiz pronounced a new 
species, having more slender teeth than S. priscus. 
Family Xipuro1pes. 
Genus Celorhynchus. 
The fossils representing this genus are considered by M. Agassiz to be the 
nasal defensive bones of a fish of the Xiphioid family, and related to Istiophorus : 
they are common at Bracklesham, and are occasionally found at Sheppey. 
* Der. rdarvs latus, Natuos gula, broad-throat. 
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