220 DESCRIPTION OF YERTBBRATE REMAINS, CHIEFLY 



Just in advance of the nares they are separated by an irregular notch narrowing 

 forward into a shallow irregular groove, about two inches long, which apparently 

 indicates the original sutural disconnection of the intermaxillaries. The notch is 

 partially occupied by a thin ridge which appears to be an extension of the nasal 

 partition or mesethmoid bone. 



The grooves proceeding forward from the prenarial fossge, about seven inches 

 in advance of the nares, are somewhat constricted, and just preceding this con- 

 striction the prenarial grooves communicate each with a large intermaxillary fora- 

 men continuous with a canal descending forward within the intermaxillary bone. 



The median position of the beak between the prenarial grooves is occupied by 

 a prominent ridge formed apparently by the union of the two intermaxillaries. 

 The forepart of this ridge in the specimen is broken away, leaving exposed to 

 view the supra-vomerine canal, extending forward as a deep groove to the end of 

 the beak. The intermaxillary ridge widens at its summit in passing backward 

 and forms an unsymmetrical clavate prominence, bending to the left, between the 

 position of the prenarial fossae. The posterior rounded extremity of the ridge is 

 continuous with the irregular elevated borders of the groove separating the back 

 part of the prenarial fossae, and the groove just mentioned is continuous with a 

 short fissure upon the intermaxillary ridge. The latter, if I am not mistaken, is 

 considered by Prof. Owen as pertaining to the prefrontals, and not to the inter- 

 maxillaries ; the prefrontals being, as I understand the matter, homologous with 

 the narial septum and the mesethmoid cartilage when this exists in this condition. 

 The intermaxillary ridge, as I have described it, in the fossil, forms the roof of a 

 long canal, made vacant from the destruction of the mesethmoid cartilage, extend- 

 ing from the position immediately in advance of the nasal passages all the way to 

 the end of the beak. If then the cartilage removed from the supra-vomerine 

 canal is regarded as an extension of the prefrontals, the ridge roofing over the canal 

 at the back as well as at the forepart of the beak I would suppose to belong to the 

 conjoined intermaxillaries. 



The supra-vomerine canal, for the accommodation of the mesethmoid cartilage, 

 extending throughout the length of the beak, is large and laterally compressed 

 cylindroid, about three-fourths of an inch perpendicularly and half an inch 

 transversely. 



The maxillaries on the upper part of the base of the beak, outside the position 

 of the maxillo-intermaxillary groove, exhibit a conspicuous rugged tract, such as 

 is also described and represented to exist in Choneziphius pJanirostris. The two 

 tracts are not quite symmetrical, that of the right side being more developed. The 



