62 H. H. SWINNERTON, 
said of the parietal. In the ascending series of bony fishes the mem- 
branous squamosal is replaced by, or incorporated in, the pterotic so 
that, as a rule, where the latter is well developed the former is ab- 
sent. In Cromeria the pterotic is large (Fig. B o.p). The squamosal, 
unlike the parietal, can never be seen from inside the cranial cavity, 
this bone can (Fig. F). 
The anterior region of the cranium shows signs of reduction, and 
is characterised by the presence of a peculiar bone (x) which seems 
to be formed by the fusion of a minute mesethmoid with the two 
nasals and with the solitary suborbitals (so) of either side. The re- 
mainder of this region is the only part of the cranium proper in which 
cartilage remains. Posteriorly it extends backwards over the para- 
sphenoid, and dorsally it presents vestiges of supraorbital bands. The 
~~ a 
0 ne GE BT / | ut Fig. F. Internal viewof the cranium 
[8 ee N of Cromeria. 25 :1. 
Fa ie ‘ Fig. G. The same of Galawias. 3 : 1. 
0. pr prootie, ro rostrale, *, + pads of 
cartilaginous tissue between the pala- 
tine, and the rostrale and maxilla respectively. The other letters are the same as in 
previous figures. 
ventral surface of both cartilaginous and ossified portions is marked 
by a deep groove in which lie the vomer and the parasphenoid. 
These bones are both edentulous and are fused with one another 
(Fig. F). 
Anteriorly the vomer is crook-shaped (Fig. F vo) and rests on a 
median cartilage which can be compared only with the rostrale of 
other Teleosts. If this comparison be correct then the vomer must 
have pushed itself between the mesethmoid and rostrale — a rather 
exceptional proceeding. 
The cranium of Galaxias (Figs. C, E) unlike that of Cromeria 
is very largely cartilaginous; so much so that, if the ovaries of this 
specimen had not been full of ripe ova, one would have felt inclined 
to regard it as an immature individual. In Cromeria the brain does 
