180 PROF. W. K. PARKER ON THE STRUCTURE AND 
On the Skull of the adult Menopome. 
This is a very flat skull, with the general outline semielliptical; the suspensoria 
form more than a right angle with the axis of the skull, and therefore are somewhat 
bent backwards. The narrowest part of the occipital ring and the condyles are alone 
behind the larger condyles of the suspensorium. 
The maxillary margins reach more than halfway to those condyles ; for these bones 
are well developed for a Urodele. 
There are two tracts of teeth in both the skull and mandibles; the whole fore palate 
and maxillary region is nearly semicircular. 
There are very large pterygoids; and these are far removed from their root, viz. the 
palatines; altogether this skull has undergone much more metamorphosis than the 
Eel-like types, viz. Proteus, Menobranchus, and resembles that of the young of an 
average “ Caducibranch ” when losing its gills. 
The inferior arches are very large, and, instead of undergoing the metamorphic 
changes and loss of substance as in the higher forms, become strongly ossified, without 
any relative change of form or size; so that this type really belongs to the “ Proteidea.” 
A. The Investing Bones of the Skull of' the Menopome. 
Roofing-plates of bone extend from the foramen magnum to the snout (Pl. XX XVIII. 
fig. 1) ; and flooring-bones extend from the edge of that passage up to the marginal bony 
are (Pl. XX XVIII. fig. 2). 
The hindermost of the upper series, the parictals (p), form, on the whole, an oblong 
tract, reaching from the foramen magnum to the ethmoidal region; they widen out 
over the auditory capsules, and are deficient on their inner edge in front, where the 
frontals (f') wedge themselves in. 
Their dilated and raised temporal process has the two forks of the squamosal (sq.) 
locking into it obliquely; their inner part, alongside the sagittal suture, is somewhat 
roof-shaped, but scarcely amounts to a ridge; together they are only three fifths the 
width of the skull-floor. The obtusely angular and notched hind part of these bones 
only partially covers the widest part of the occipital cincture. 
The frontals (f) are only half the size of the parietals; together they cover a 
Y-shaped tract; for these bones are narrow toothed wedges behind, whilst in front 
they widen somewhat, and are divaricated to let in the nasals (7), much more than the 
parietals did to take them in. 
Their outturned fore end is overlapped by the round-edged ascending plate of the 
maxillaries (m«); and this part almost reaches the outer nostril (¢.n). Here the nasal 
roof is exposed behind the passage as a pyriform tract of cartilage, whose point ends 
between the frontal and nasal. 
The nasals (7) have a toothed suture between them, which continues the open 
sutural line along the low ridge of the skull; they also are wedges, broad in front and 
