2 



SIR R. OWEN ON A TRIASSIC SAURIAN. 



cephalus and BatracJiosaurus, has also furnished the subject of the 

 present paper. 



Characters of the skull and teeth, more or less mutilated in the 

 original specimen of Galesaurus, have been brought to light by careful 

 removal of the adherent matrix from the present fossil, under the 

 superintendence of my friend Mr. W. Davies, Assistant in the 

 Department. 



Cranial and dental characters, so exposed, are given in the annexed 

 drawings of the natural size (PI. I.) ; to one of which (fig. 2) is added, 

 in outline, the better-preserved occipital region of the typical speci- 

 men of Galesaurus, now also in the Geological Department. 



In both specimens the reptilian nature of the fossil is exemplified 

 by the single occipital condyle (figs. 2 & 3, 1) and by the degree in 

 which the ex- (2) and supra- occipitals (3) slope forward as they rise 

 to join the parieto-mastoid elements, 7-8. The restricted propor- 

 tions of the brain are concurrently exemplified by the parieto-frontal 

 ridge-like roof and steeply sloping side-walls of the cranial cavity 

 (fig. 2, 7). The mass of the temporal muscles is indicated by the 

 wide span, Z, of the strong zygomatic arches, the parietal boundaries 

 of which meet and develop a median crest, to which the frontals, 11, 

 also contribute a small proportion. No trace of sagittal suture 

 remains: the chief difference in this part of the cranium from a 

 mature male of a placental or marsupial Carnivore is the retention 

 of the evidence of a primordial " gullet-tract," manifested by the 

 " pineal " or " infundibular " orifice (fig. 2, 7)*. The orbits, 0, have 

 a strong uninterrupted bony rim, formed above by the pre- (14) and 

 post- (12) frontals, which unite suturally and exclude the mid 

 frontal (figs. 1 & 2, 11); the orbital frame is completed before and 

 below by the lacrymal, maxillary (21), and malar (20) bones. A 

 strong, vertically broad element (s) of the zygomatic arch seems to be 

 excluded from the orbit b} T a suturally joined malar and postfrontal ; 

 the arch bends outward to augment the space for the temporal 

 muscle, and broadly joins the mastoid to form the hind wall of the f 

 wide temporal fossa ; the muscles so indicated relate to vigorous 

 working of the canine weapons. 



The plane of the orbit slopes forward and from above downward 

 and outward (figs. 1 & 2, 0, 0). The fronto-nasal suture runs across, 

 in a line with the fore border of the orbits. The nasals (15) diverge 

 anteriorly to form the sides of a single almost terminal outer nostril 

 (n), which exposes the fore border of a bony septum. In some other 

 Triassic Reptiles (Oynosuchus, e.g.) the nostril is single. The pre- 

 maxillaries complete the nostril. The palatal region (fig. 3) repeats 

 the same general characters as in previously described Theriodonts 

 where it has been exposed, e. g. in Dicynodon leoniceps {op. cit t 

 pi. xxvi.), Oudenodon magnus (ib. pi. lvi.), Oudenodon brevirostris 

 (ib. pi. lviii.). 



The pterygo-maxillary vacuities (fig. 3, y) are large, but relatively 



* See ' Essays on the Conario-hypophysial Tract, and on the Aspects of the 

 Body in Vertebrate and Invertebrate Animals.' By Richard Owen, F.R.S. &c. 

 8vo, 1883 (Taylor and Francis, Bed Lion Court, Fleet Street, London). 



