6 Mr. C. W. Andrews on a Group of 



teeth, and are different in many other respects. It may 

 here be remarked that Hesperornis cannot be an ancestral 

 form of the Stereornithes, since it is ab'eady too specialized 

 (e. g. in the extreme reduction of the wings). 



In his description of the skull Ameghino lays much stress 

 on the fact that the orbit is not at all separated from the 

 antorbital fossa ; but since the lachrymal is commonly very 

 loosely united to the skull, it might easily have been somewhat 

 displaced in the fossil, and it may be suggested that the bone 

 described as the supraorbital may, in fact, be the lachrymal. 

 The descending lamina, marked si in the figure (p. 3), would 

 then correspond to the descending process of the lachrymal, 

 which in most birds forms a more or less complete division 

 between the orbit and antorbital fossa, as in many birds this 

 process unites inferiorly with the jugal. The bone marked II, 

 and regarded as a descending portion of the lachrymal, would 

 then probably be a portion of the ethmoid. In this region of 

 the skull of Phororhacos there seems to be a certain resem- 

 blance to that of the Seriema [Cariama). In this form 

 also the lachrymal sends down a branch, which is connected 

 with the jugal by a small distinct rod-like element, described 

 long ago by Burmeister "^ and apparently occurring in 

 Cariama only. In Ameghino's figure there is some indica- 

 tion that the element marked Is may also be distinct ; and if 

 it should turn out that this is the case, it would be a point of 

 some interest. In Cariama also, in front of this boundary 

 of the orbit and at the bottom of the antorbital fossa, 

 there is another vertical bar of bone, which consists of a 

 portion of the ethmoid and would correspond with that marked 

 II in the figure. In Psophia the lachrymal is small and does 

 not extend to the jugal. In both Psophia and Cariama the 

 angle of the mandible is truncated. In Cariama the nostrils 

 are pervious, as they also appear to be in the fossil, although 

 the septum may have been lost. In Chauna also the 

 lachrymal is small and does not extend to the jugal, and the 

 mandible has a very large angular process. Cathartes, again, 

 differs in many respects, though in the form of the nostrils 



* "Beitr. z. Naturgesch. d. Seriema,'' in Abb. iiat. Ges. z. Ilalle, i. 

 p. 11 (1854). 



