112 ALUS. [Vol. XVIII. 



backward beyond the anterior edge of the preoperculum, over- 

 lapping that bone externally to a greater or less extent. The sec- 

 ond bone distal to this large bone is the second one posterior to 

 the lachrymal. It is always much more convex externally than 

 any of the other bones of the series, and seems to mark a definite 

 place in the infraorbital chain. Just what its significance is I am 

 unable to determine, but it seems to hold a certain definite relation 

 to a part of the infraorbital lateral canal and will be again referred 

 to in describing that canal. Its dorsal edge simply touches and is 

 bound to the edge of the adjoining bone, the adjoining edges of 

 the other, more dorsal bones of the series being similarly related 

 to each other. Its ventral edge, on the contrary, is overlapped by 

 the dorsal edge of the bone next distal to it and that bone has a 

 slight sliding motion upon it. The latter bone is, in turn, over- 

 lapped by the dorso-posterior corner of the lachrymal, and so 

 bound to that bone that a slight turning, rather than sliding mo- 

 tion is possible between them. This bone, the first one posterior 

 to the lachrymal, I have considered as a suborbital bone, the other 

 bones of the series being considered as postorbital. 



The Lachrymal {LA) is a large four-sided bone, directed 

 forward and upward. The anterior end of the bone is consider- 

 ably wider than the posterior end, and the antero-ventral edge 

 considerably longer than the dorso-posterior edge. Immediately 

 behind the antero-dorsal corner of the bone there is, in its dorso- 

 posterior edge, a semicircular indentation, the edges of which are 

 thickened so as to form an articular surface. It articulates with 

 the antero-ventral surface of the outer end of the palatal process 

 of the preorbital ossification, and is firmly bound to that process 

 by fibrous tissues. The anterior end of the bone extends forward 

 ventr^ to the curved, anterior end of the palatine, and is attached 

 by fibrous or ligamentous tissues to the anterior end of the max- 

 illary, the attachment being mainly to that short process of the 

 maxillary that overlaps externally the premaxillary and serves for 

 the insertion also of the ligaments that arise from the ethmoid 

 and nasal bones. Where the lachrymal passes ventral to the head of 

 the palatine it is often slightly cut out so as to fit against that bone. 

 The lower edge of the bone is thin, like the outer edges of all the 

 infraorbital bones, and extends ventrally slightly beyond the ven- 



