SS2 Proceedings of the 



Skeleton. 



The skeleton of Malapterurus, like that of other Siluridae, 

 is remarkable for the flattened shape of the head, and the 

 tendency to coalescence of the facial bones. 



The cranium may be divided, for purposes of description, 

 into two parts — the cerebral and the nasal. The former por- 

 tion is, in this species, somewhat of a square form, but tapers 

 a little to the front; the other part is much narrower and longer 

 than the first. Looked at from above, it has this peculiarity, 

 — viz., that the parietal bones are absent. The supra-occipi- 

 tal bone is well developed ; it has no dorsal crest. It articu- 

 lates broadly with the great frontal bone in front, and laterally 

 with the mastoid and ex-occipital. The ex-occipital bone pre- 

 sents a foramen for the great lateral nerve, and a process 

 with which the scapula is articulated. The mastoid bones 

 complete the posterior margin of the skull, and form the larger 

 part of the lateral margins of the cerebral part. Each pre- 

 sents three processes, the two posterior of which are connected 

 with a Y-shaped cartilaginous representative of a supra-tem- 

 poral set of bones, and the anterior with a bone which joins 

 the infra-orbital range. The post-frontal bone completes the 

 lateral margin, and combines with the great frontal to form 

 the anterior margin of the cerebral part of the cranium. It 

 presents a long process, which projects laterally from the skull, 

 and to which the sub-orbital chain of bones is articulated. 

 The great frontal bone is broad behind, where it enters into 

 the formation of the cerebral part of the cranium, narrow and 

 bifurcated in front, where it forms part of the roof and sides 

 of the nasal portion. By its bifurcation it forms the posterior 

 and lateral walls of a long opening, which is completed an- 

 teriorly by the nasal and pre-frontal bones. The great fron- 

 tal bone articulates with the supra-occipital, mastoid, and post- 

 frontal bones posteriorly, with the orbito-sphenoid bones and 

 inter-orbital plate, placed laterally and beneath it, and an- 

 teriorly with the pre-frontal and nasal bones. 



Turning to the under surface of the skull, we observe that 

 there is no petrosal bone. The basi- occipital bone underlies 

 at its posterior extremity the thin body of the first vertebra. 



