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In larvae 55 and 80 mm in length, I find, occupying the place of the alisphenoid bone of 

 Parker's descriptions, a V-shaped process of the parasphenoid which embraces the mesial edge of an 

 anterior plate-like process of the proötic cartilage. This process of the proötic cartilage occupies the 

 place of, and certainly is the basipterygoid process of Parker's descriptions, but it has a short free 

 mesial edge not shown by Parker. The anterior edge of the V-shaped process of the parasphenoid 

 is elosed by a rounded union of the plates that form its two limbs, and the limbs are here both 

 short, extending laterally only about one third the width of the cartilage. This rounded anterior 

 edge of the process, and the corresponding edge of the cartilage beyond it, together, give articulation 

 to the metapterygoid. The point of the V 'of the V-shaped process is directed mesially toward the 

 lateral edge of the parasphenoid, but it does not, in its anterior portion, quite reach that edge. 

 Posteriorly it meets and fuses with the edge of the parasphenoid, thus becoming a part of the 

 ascending process of that bone. The dorsal (internal) limb of the V there vanishes, while the 

 ventral (external) limb becomes prolonged into that tall plate of the ascending process of the 

 parasphenoid that lies against the external surface of the proötic cartilage. In 19 mm and 25 mm 

 specimens, which I have also examined, the internal limb of the V-shaped process has not yet 

 developed, the external limb alone being found. The V-shaped process of older specimens is 

 thus, in these young larvae, simply a plate-like part of the ascending process of the parasphenoid 

 which, projecting forward, forms the lateral boundary of a narrow space, or notch, between itself 

 and the lateral edge of the body of the parasphenoid. Through this notch the efferent pseudobranch- 

 ial artery runs upward, and then turns mesially between the body of the parasphenoid and the 

 overlying cartilaginous basis cranii, to join and completely fuse with the internal carotid. Im- 

 mediately posterior to the notch, the ventro-mesial edge of the base of the basipterygoid process 

 of the proötic cartilage fuses with the ventral surface of the lateral edge of a short band-like portion 

 of the cartilage of the region, this latter cartilage bounding the space in which the hypophysis lies. 

 Posteriorly this band is continuous with the parachordal cartilage, while anteriorly the lateral end 

 of its nearly straight anterior edge is continuous with the thickened ventral edge of the cartilage 

 of the alisphenoid region; that thickened edge of the alisphenoid cartilage being continuous, anter- 

 iorly, with the hind end of a median portion of the trabecular cartilage. Whether the short band 

 of cartilage is of trabecular origin, or not, I can not positively teil, but it would seem as if the 

 trabecular cartilage could not extend posteriorly, on either side, beyond the hind end of the 

 thickened ventral edge of the alisphenoid cartilage. This being the case, the short band of cartilage 

 would represent the anterior end of the parachordal cartilage, and as such I consider it; the hypo- 

 physis then lying between the anterior ends of the parachordal cartilages. Parker shows this part 

 of the chondrocranium of Lepidosteus somewhat different from what I find it, and he considers the 

 cartilage of this region as of trabecular origin; but he also considers the basipterygoid process as 

 of trabecular origin, and that cartilage, being a process of the proötic cartilage, must certainly be of 

 post-trabecular origin. 



The basipterygoid process of Lepidosteus, it may here be stated, has so closely the position 

 and the relations to the nerves and blood vessels of the region that the basipterygoid process of 

 Lacerta has (Gaupp, '00, p. 537), that it must be the homologue of that process. In Amia, it is 

 apparently represented in the little cartilaginous process that is perforated by the efferent pseudo- 

 branchial artery (Allis, '97a), and that rises from the lateral edge of what is apparently the hind 

 end of the fused trabeculae. In most teleosts the process seems wholly wanting. 



