190 PISCES. 



bone is reckoned not improbably by some as belonging also to the 

 articular division of the temporal. The whole of the quadratal bone 

 abuts in front arid superiorly against the inferior wings of the sphe- 

 noid. In cases where several of the bones now described are want- 

 ing, or have coalesced together, four, three, or only two bony pieces, 

 may compose the articular portion of the temporal. Thus in Cy- 

 prinus and Esox we find five, but in most genera, as Perca, Pleuro- 

 nectes, and Cobitis, only four of these elements. The quadratal 

 bone, e. g. Zeus, Silurus, and Heterobranchus, is formed of three 

 pieces. Two pieces only, firmly united by suture, are fouud, e. g. 

 in Muraena and Mursenophis, where this bone more resembles in 

 form the os quadratum of the higher Vertebrata. A pair of mostly 

 small flat parietal bones, which are situated upon the upper surface 

 of the cranium, between the occipital, temporal, and frontal bones, 

 are very generally present. In front of these lie the double frontal 

 bones, mostly of considerable size, and to which the ethmoid is 

 affixed in front. This latter bone consists of a middle azygos piece 

 or lody, and two large lateral ethmoids, which have been viewed by 

 many as particular bones under the name of anterior frontah. Spaces 

 forming fontanelles occasionally intervene, e. g. Silurus, Cobitis, be- 

 tween the frontals and also the parietal bones. The distinct want 

 of symmetry in the bones of the two halves of the cranium in the 

 Plaice and Flounder is another osteological peculiarity deserving our 

 attention. 



The greater proportion of the Facial bones in the Osseous Fishes 

 admit of being very readily referred to their analogues in the higher 

 Vertebrata. The upper jaw consists very generally of an anterior 

 pair of intermaxillary bones, mostly supporting teeth, and of a su- 

 perior maxillary, occasionally very rudimentary, situated behind 

 these, and scarcely ever furnished with teeth. In the Carp tribe 

 both bones are devoid of teeth ; the intermaxillary bone is usually 

 the smallest of the two, but is largest in Spams and the Fishes of 

 the Eel kind e. g. Mursenophis, in which the intermaxillary and 

 vomer appear to have coalesced, while the superior maxillary sup- 

 ports teeth. In some cases the latter bone coalesces with the vo- 

 merine, palatal, and nasal bones to form a single bone, which unites, 

 however, with that of the other side by suture, as in Orthagoriscus 

 and Diodon. The superior maxillary bone is very small and rudi- 

 mentary in Silurus, and is even absent in Balistes, where, however, 

 the intermaxillary is much developed. A second bony piece in rare 

 instances, e. g. in the Trout, Pike, and Herring, is situated above 



