REPTILIA: NOTHODON 19 



forward, as in other Cotylosauria, to form the posterior border of 

 the nares.* 



The postfrontal, a short and thick bone hke the prefrontal, has 

 a thickened sutural border posteriorly for the postorbital. The 

 parietals are rather small bones, touching each other for a short 

 distance only in front and behind the "enormous" parietal fora- 

 men. In front they articulate by a broad, underlapping squamous 

 suture with the frontal, on the outer side with the postfrontals 

 and postorbitals, and with another element perhaps between them 

 and what I here call the squamosals. Back of the parietals 

 are the broad dermoccipitals, which are blended on the upper 

 side with the supraoccipitals almost indistinguishably. I believe, 

 however, that their sutural separation follows about the line as 

 I have drawn it. On the under side, the cartilage supraoccipital 

 forms the whole of the superior surface of the brain chamber 

 posteriorly and on either side includes more or less of the semi- 

 circular canals and otic cavity. The brain surface runs upward 

 and forward, in one specimen narrowing into a groove which leads 

 into the pineal chamber; in the other specimen the anterior 

 part of the groove has been broken away cleanly from the suture 

 connecting the supraoccipital with the dermoccipital. It is clear 

 that the supraoccipitals met the parietals in the middle, wholly 

 excluding the dermoccipital from contact with the brain. The 

 pineal opening, as has been said, is enormously large, twenty- 

 three millimeters in longitudinal diameter, by about twenty in the 

 transverse diameter. Its walls are seven millimeters in height, 

 vertical throughout the thickness of the roof bone, with sharp and 

 rather protuberant edges below, save where the cavity continues 

 back into the narrowed brain roof of the supraoccipital bone. 



' I have for several years been much inclined to accept the conclusion reached by 

 Jaekel that the real lachrymal of the reptiles is homologous with the so-called pre- 

 frontal of the reptiles and amphibians, but have been loath to accept the name proposed 

 for the so-called lachrymal by Jaekel, "postnarial." Gaupp's more recent researches 

 seem to prove the contention of Jaekel, but I am not at all inclined to accept the name 

 proposed by Gaupp for the bone, "adlachrymal," in lieu of Jaekel's name. In the primi- 

 tive condition of the bone it does not enter into the formation of the orbit at all, but 

 forms a part of the posterior border of the nares, so that objection to the term "post- 

 narial" is not pertinent on the grounds of its position, though remote from the nares in 

 the higher forms. Nor can I see why the term "adlachrymal" is any more appropriate. 



