PRELIMINARY DESCRIPTION OF SOME NEW LYSTROSAURL 
By Dr. E. C. N. van Hop: pen, M.I. 
The Lystrosaurus material in the Transvaal Museum has steadily increased 
of recent years, and its collections now contain some forty developed 
skulls of this genus. The peculiarities of many of these specimens and 
the new forms were not made known before, because it was thought better 
to acquire a good many specimens before giving any description. The 
collection has now grown tb such an extent, however, that longer delay 
of discussion would not find justification in lack of material. On the 
other hand, the character of most of the descriptions of the known forms 
is such, that identification of Lystrosaurus material without the aid of the 
type specimens is nearly impossible. It seems that a revision of the genus 
is a pressing necessity. As this could not be undertaken by me at present 
only two other ways remained, namely, either to abandon the idea of 
describing our material or to do it with a great risk of producing synonyms. 
The latter way was chosen, and care was taken to reduce this risk to a 
minimum. A preliminary description is hereby given of new forms in 
the collection. A description in extenso may be expected in a short time. 
Lystrosaurus Breyeri , n. sp. 
Relatively much narrower between the outer edges of the prefrontals 
than latirostris. Bedims and plaiyceps are relatively broader and Aljredi 
narrower in the parietal region. Murrayi is relatively narrower and as 
in vertical} s the distance of the septomaxillary from the oral edge is 
relatively much greater. In hoops, on the other hand, this distance is 
much smaller compared with the breadth over the prefrontals. The 
breadth between the edges of the prefrontals in jrontosus greatly exceeds 
the length of the premaxillary. In Breyeri the premaxillary is longer 
than the prefrontal breadth. Andersoni and Mccaigi are much narrower 
between the hinder upper corners of the orbital rims. Putterilli is 
relatively broader between the upper corners of the orbital nms and much 
broader in the parietal region. 
The above has been gathered from the following measurements : — 
1. Length of the premaxillary. 67 mm. 
2. Distance from the front end of the septomaxillary 
to the oral edge. 39 mm. 
3 . Greatest breadth between the outer edges of the 
prefrontals 64 mm. 
4 . Breadth between the hinder upper corners of the 
orbital rims 44 mm. 
5 . Breadth between the parietal ridges over the parietal 
foramen 15 mm. 
6. Breadth of the snout at upper end of canine ridges. 58 mm. 
