674 



PKOF. H. Gr. SEELEY ON THE EEPTILE 



anatomy of no ordinary kind, since the maxillary bone does not 

 enter into either the orbit or the anterior nares of the crocodile, and 

 it certainly does not enter in any known Dinosaur into the external 

 wall of either of these vacuities. Agreeing with Biinzel, that the 

 margin which he regards as the anterior border of the orbit is cor- 

 rectly identified, I regard the perforation which he terms nasal as 

 the preorbital vacuity characteristic of Teleosaurs, and more or less 

 developed in various Dinosaurs. The bone between the orbit and 

 the preorbital vacuity is always the lachrymal; and I therefore 

 identify the lachrymal bone as united by suture with the maxil- 

 lary. The length of its base is 2 centim. ; but it is fractured 

 superiorly, and therefore its outline cannot be stated, further than 

 that it appears to have been triangular. The posterior margin 

 is concave, rounded and thickened, with an indication of a groove, 

 which may have had relation to the lachrymal canal. The surface 

 is sculptured with somewhat oblique ridges, which are short and 

 irregular, and deeper than the sculpturing on the maxillary. The 

 suture with the maxillary is straight but slightly oblique, so that it 

 laps a little further down on the inner than on the external surface. 

 The preorbital vacuity only shows a small portion of its basal 

 margin, which is rounded. The lachrymal bone in front of it is 

 thin, and gives the aspect of the vacuity having penetrated ob- 

 liquely inwards and forwards. A small portion is preserved of a 

 suture on the superior surface, which is straight and parallel to the 

 alveolar surface, or but slightly inclined forwards. Hence it may 

 reasonably be identified as the suture for the nasal bone. The 

 depth of the bone from the nasal suture to the alveolar border 

 is 22 millim. Anteriorly the bone is fractured, so that there is no 

 indication either of its length or of the length of the nasal suture, 

 or of the nature of its relation to the premaxillary bone. The pos- 

 terior end is also fractured ; but just below the orbital border there 

 is a minute indication of a suture, evidently indicating the malar 

 bone, and showing that its relations were the same as in Dinosaurs. 

 The surface of the maxillary bone is marked with an indefinite 

 rough sculpturing, which, in the upper part, has a tendency to 

 assume a linear character ; and the hinder part is somewhat lightly 

 pitted. The internal surface is necessarily irregular ; and its appear- 

 ances may be passed over in so far as they relate to the region 

 above the palate ; but above the alveoli the bone evidently developed 

 a horizontal palatal plate, which has been almost entirely broken 

 away. It appears to have been notched out posteriorly into a post- 

 maxillary vacuity, such as is seen in the crocodile, since the hinder- 

 most 1| centimetre is a smooth, sharp, somewhat concave margin 

 bordering the alveoli. 



It is very difficult to understand the alveolar structure from an 

 inspection of Bimzel's plate, since it gives the appearance of a double 

 row of tooth-sockets : this is due to the circumstance that while the 

 tooth-sockets (in which most of the teeth still remain) are placed 

 close to the outermost alveolar border, there is, internal to them, a 

 parallel series of pits which are broad and shallow, and are, I think, 



