CLIMATIUS SCUTIGER. 



67 



interspace between the pectoral and ventral fins is armed with 

 three pairs of defensive spines, similar in character to, but somewhat 

 smaller than, the ventral spines. Properly speaking, they are 

 elongated scutes, forming part of the dermal envelope. They have 

 a shallow cavity where attached to the integuments, and the cast 

 of this depression when the spine is removed much resembles a broad 

 scale. The great development of this cutaneous armature has 

 suggested the specific affix I have given to this fish. Some other 

 genera of Acanthodeans show a tendency to this character ; 

 for instance, Professor Agassiz describes the occurrence of two 

 small ventral spines, situated between the pectoral and ventral 

 fins, in Diplacanthus crassispinus, and some specimens of Acan- 

 thodes Mitchelli have faint traces of the same peculiarity. The 

 anterior dorsal spine is inserted over the central pair of ventral 

 scutes, or nearly midway between the pectoral and ventral fins. It 

 is larger than the pectoral spine, and slopes backwards at a con- 

 siderable angle. The spine figured by Professor Agassiz in the 

 " Poissons Fossiles du Vieux Gres Rouge,'' plate 32, fig. 25, is pro- 

 bably the anterior dorsal spine of his species. The great inclination 

 of the spine suggested the generic title Glimatius. The second 

 dorsal spine is longer, straight er, and more slender than its com- 

 panions. The anterior margin is quite straight, but the hinder 

 limb bulges out about midway between the apex and the base. 

 The anal spine is situated slightly in advance of the base of the 

 second dorsal spine. It is intermediate, both in size and character, 

 between the two dorsal spines, being longer and straigliter than the 

 one, but shorter and more bent than the other. Some specimens 

 retain faint traces of the organs attached to these spines. There is 

 a doubt whether tliey were composed of true fin rays or not. My 

 own opinion is that they w^ere membranous, as in the other genera 

 of Acanthodean fishes, and that the appearance of striae is to be 

 attributed to the impression of the longitudinal series of minute 

 scales with which they were invested. I have already alluded to 

 the extraordinary development of certain scales on the ventral 

 surface of the body. A repetition of the same character, although 

 not to the same extent, occurs on the dorsal ridge, the interval 

 between the occiput and the first dorsal fin being roofed by a 

 single row of umbonated scales, not unlike those occurring in 

 the genera Scmrorhamphus, Eurypholis, and Dercetis, although not 

 so large in proportion to the dimensions of the fish. The scales on 

 the other parts of the body are very minute, and resemble those of 

 the other Acanthodean fishes in form and arrangement. The 



