72 
Annals of the Transvaal Museum. 
In the skull of latirostris described some time ago ( 4 ) these dimensions 
are respectively : 180, 224, 169, and 115 mm., from which may be seen 
that the present skull is 10 cm. longer, 11 cm. broader, and 4 cm. higher. 
The longest Lystrosaurus skull, L. Mccaigi Seely, was described by 
Broom in 1903 (2). A sketch of a side view was added, but neither sketch 
nor description can be used for accurate comparison. My cwn obser- 
vations on this skull gave the following : 
The distance between the front edge of the jaw and the 
hinder end of the mutual suture of the parietals is 387 mm. 
Breadth of the skull across the lower ends of the post- 
orbitals 178 mm. 
Height of the occipital plate, taken from the lower ends 
of the paroccipital processes to the front end of the 
mutual suture of the parietals on the upper surface 197 mm. 
The occipital plate is hollow and the upper surface of the skull is 
turned into a narrow furrow all through lateral compression. The pre- 
orbital portion has also been compressed laterally. 
Breadth of the skull between the upper and hinder corners 
of the orbital cavities 75 mm. 
Length of the preorbital portion measured from the upper 
edge of the jaw along the central ridge of the pre- 
maxillary to the pair of protuberances on the pre- 
frontals — 
to the beginning of the protuberances 230 mm. 
to the end of the protuberances 280 mm. 
to the middle of the protuberances 255 mm. 
Breadth of the premaxillary above the exterior nares. . 48 mm. 
Length of the upper surface of the premaxillary 165 mm. 
The length of the septomaxillary measured along the 
suture with the maxillary ( is at least 75 mm. and 
may even be 100 mm. 
The distance from the hinder end of the septomaxillary 
to the place where the suture between the nasal 
and the premaxillary disappears in the nose 64 mm. 
Length of the nasals 122 mm. 
Breadth of the preparietal 16 mm. 
(The preparietal may have been as broad as that of Putterilli.) 
Diameter of the orbital cavity antero-posteriorly 70 mm. 
If these dimensions are compared with those of Putterilli it will b e 
seen that the skull of Mccaigi Is much longer and higher than that o^ 
Putterilli. On the other hand the skull of Putterilli is absolutely 
broader between the upper and hinder corners of the postorbital cavities 
than the skull of Mccaigi (see under Frontals). Even if some allowance 
is made for compression the skull of Mccaigi still remains relatively 
narrower. I have therefore concluded that the two specimens belong 
to different species. Other differences will be considered in discussing 
the bones composing the skull of Putterilli, 
