170 EDWARD L. RICE 
essentially duplicated in embryonic Echidna (Gaupp, ’08 a). 
In the higher mammals the carotids enter the skull lateral to 
the homologue of the trabeculae and independently of the 
fenestra hypophyseos; conditions in the marsupials are de- 
seribed by Broom (’09) as intermediate between those in Echidna 
and in the placentals. In the reptiles there are minor variations. 
In Emys, Kunkel (12 b) reports the absence of definite incisurae 
caroticae; on the other hand, Fuchs (712) describes the original - 
fenestra hypophyseos of Chelone as divided by a transverse bar 
of cartilage and the longitudinal intertrabecula into an anterior 
definitive fenestra hypophyseos, which is soon obliterated, and 
two posterior foramina for the carotid arteries. The inde- 
pendent carotid foramina of Chelone were noted by Gaupp (’05 
b). Nick (12) also describes an intertrabecula in Chelone and 
Dermochelys; Parker (’80, ’83) has recorded the same structure 
in Chelone and the crocodile. It is entirely lacking in Eumeces. 
For a short distance in front of the fenestra hypophyseos the 
trabeculae lie in close contact, but are not actually fused with 
one another (fig. 23, trab.); they then unite gradually but com- 
pletely, and are continued forward in the thickened basal mar- 
gin of the high interorbital septum (fig. 3, sep.i-o.) characteristic 
of the orbital region of reptiles generally. Only in the snakes 
is the septum reduced to a connective-tissue plate (Gaupp, 
705 b) or entirely lacking (Parker, ’78; Peyer, 712). . In Emys, 
Kunkel (12 b) describes a conspicuously paired structure of the 
septum; in Kumeces any suggestion of such a paired character 
is confined to the ventral margin and the extreme posterior end— 
the region of transition from the trabeculae. According to 
Schauinsland (’00) and Howes and Swinnerton (’01), the tra- 
beculae are much less closely united with the interorbital septum 
in Sphenodon, especially in younger embryos, than in Eumeces, 
and in Chelone Fuchs (712) denies any participation of the tra- 
beculae in the formation of the septum. 
The posterior free margin of the interorbital septum (fig. 3) 
is broken by two notches—a lower narrow incision just above 
the trabeculae and a much larger indentation occupying the upper 
two-thirds of the margin of the septum; between the two is a 
