150 Edward Phelps Allis jr., 



Amia and Polypterus are strictly homologous. What place, if any, 

 the vertical line of sense organs on the end of the snout of Conger 

 should take in these homologies, I am unable to determine, not having 

 been able to determine its innervation. 



In my 80 mm Conger the anterior ethmoidal primary tube, on 

 each side, traversed an opening in the lateral wall of this part of the 

 skull. The two posterior tubes, one on each side, traversed a single 

 large median opening, much larger than is needed for the passage of 

 the tubes alone. In the adult these two latter tubes traverse separate 

 openings, one on each side, the remainder of the single median opening 

 of younger stages being usually wholly closed. In one adult, however, 

 a part of this large opening of larvae was retained as a round median 

 foramen (fig. 17), Avhich perforated the skull, between the four pro- 

 cesses that give passage to the four ethmoidal primary tubes, and led 

 directly into the median sensory chamber. The foramen was entirely 

 closed externally by ligamentous tissue, but it would seem to be an 

 inherited remnant of the median primary tube that should normally 

 have here been developed. 



This median, sensory, ethmoidal chamber of Conger, which un- 

 doubtedly has its exact homologue in the median ethmoidal chambers 

 referred to in the descriptions of the three other Muraenidae examined, 

 is unique, so far as I can find, in fishes heretofore investigated, ex- 

 cepting only in Polyodon (No. 8). What its full significance is, I have 

 been as yet unable to determine. It lies in what is quite certainly 

 an ethmoid bone, formed, one would naturally suppose, by the com- 

 plete fusion of the two well known dermal and cartilaginous com- 

 ponents of that bone. But no indication whatever of preexisting 

 cartilage, nor of any remnants or vestiges of enclosed cartilage could 

 be found, even in my youngest specimen, and the bone did not differ, 

 in appearance, in any respect from the bones elsewhere related to the 

 lateral sensory canals. Comparison with Polyodon would, moreover, 

 indicate that the bone was a purely dermal or membrane bone. Other 

 components of the skull of Conger, certainly of purely dermal origin, 

 have completely fused with this ethmoid bone, even in my youngest 

 specimen. One of them is certainly the piscine vomer. Another would 



