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separates into two parts, one of which turns upward and backward, in the posterior one of the two 

 infranasal bones shown in the figures, while the other part traverses the anterior one of those two 

 bones and then enters and traverses the membrane component of the mesethmoid. This latter bone 

 alone, if it lodges two latero-sensory organs on either side, or this bone together with the anterior 

 infranasal bone, if each of the bones lodges but a single organ on either side, is accordingly the homo- 

 logue of the supraethmoid (median dermal ethmoid) of Amia; and in Elops, as in Amia, the one or 

 two bones have not yet become incorporated in the premaxillary as its ascending process. The posterior 

 infranasal bone alone (or that bone together with the anterior one, if this latter bone be not a part 

 of the median dermal ethmoid) is the homologue of the antorbital bone of Amia, and this antorbital 

 bone, traversed bv a latero-sensory canal, has also never heretofore been described in any teleost, 

 so far as I can find, unless it be in certain of the Siluridae (Allis, '98). This antorbital bone of Amia, 

 and hence also the bone of Elops, is represented in Polypterus, as I have already shown ('00b), in the 

 infranasal process of the premaxillary of that fish, and, judgirig.from a recent work by Gaupp ('05), 

 it must be the homologue of the septomaxillary of Amphibia and higher vertebrates. It is of 

 dermal origin, as the septomaxillary is, and so closely resembles that bone in general position and 

 relations to other bones that it seems quite unquestionably to represent it before it has acquired its 

 nasal plate; that plate being a special and secondary acquisition, as Gaupp has shown. 



In Macrodon, which I have examined, the premaxillary has a process similar to that in Salmo, 

 and similar also to that shown by Sagemehl in Erythrinus, where that author considers it as an as- 

 cending process. This process in Macrodon articulates by its mesial edge with the lateral edge of the 

 dermal component of the mesethmoid, and is widely separated from its fellow of the opposite side, 

 exactly as Sagemehl's figures show for Erythrinus. On its internal surface there is a raised portion 

 which gives articulation to the lateral surface of the long anterior articular end of the maxillary, and 

 that the process is simply an articular process seems quite unquestionable, the bone then having no 

 ascending process. And this is strictly as it should be, for the dermal supraethmoid is here said by 

 Sagemehl to be fused with the primary mesethmoid to form the median mesethmoid bone of the fish. 

 The supraethmoid of Macrodon would seem, however, to have been developed in relation to the 

 median one only of two ethmoid latero-sensory ossicles on each side, and to represent a membrane 

 component only of those ossicles, no latero-sensory organs here being found. The membrane com- 

 ponent of the lateral one of the two ethmoid latero-sensory ossicles may then be here fused with the 

 articular process of the premaxillary; for the outer surface of this process in Macrodon comes to the 

 level of the adjacent dermal bones and has surface markings quite similar to those on those bones. 

 In Elops the anterior infranasal bone, assumed to represent the lateral one of the two ethmoid latero- 

 sensory ossicles on either side, and which is traversed in that fish by a latero-sensory canal, lies directly 

 superficial to and in contact with the articular process of the premaxillary. 



It may here be further stated, that I find, in my specimen of Macrodon, the bone called by 

 Sagemehl ('84b, p. 95) the accessory palatine, and that, so far as can be judged from my somewhat 

 dilapidated specimen, it is developed in the maxillary breathing valve of the fish. This, if correct, 

 is important, for it would then be the homologue of the so-called vomer of Polypterus, a bone which 

 I, in an earlier work ('00b), identified as the maxillary breathing valve bone of that fish. It has never 

 heretofore been recognized in any teleost. 



In Osteoglossum, according to Ridewood's ('05a) figures, the premaxillary has no ascending 

 process, and Ridewood says that, in this fish, the ,, mesethmoid is a small rhombic bone of ectosteal 



