242 MR. W. K. PARKER ON THE STRUCTURE AND 
tion of such diverse forms into a single Order of the Eutheria. But in this, as in many 
other types of Vertebrata, the highly compound cranial region retains a large number 
of archaic characters that are suppressed or lost in the body, and especially in the soft 
organs.” 
The investing bones of the skull of the embryo of Rhynchocyon. 
In this apparently nearly ripe embryo the bones as seen from above (Plate 36, 
fig. 1) form a nearly perfect roof to the rather long cranium. Of these the fore- 
most, or nasals (7.), are only moderately long and broad ; they are two-thirds the length 
of the frontals (f:),and of the same length as the sagittal suture. Rounded in front, they 
widen up to the triradiate suture, where they, the premaxillaries, and maxillaries 
(px., mx.), meet ; they are then somewhat pinched, and widen a little, once more, to 
unite with the frontals. 
In strong contrast with what we see in the Mole and the Shrew, the frontals (/) 
are nearly as wide as, and nearly one-fourth longer than, the parietals (p.), and 
although, together, they have a well-formed mid-orbital waist, they are very wide even 
there. Towards the still open, four-cornered fontanelle (f0.), the main upper part of 
these bones is gently convex ; this convexity narrows, forwards, and there is a definite 
fossa marking it off from the supraorbital margin, which is very neat and finished, and 
quite unlike what we have just seen in the more typical Insectivora. Slightly over- 
lapping the frontals, and wedging into their lower and hinder edge, the parietals ( p.) 
give a great breadth to the intertemporal region; their convexity, above, is greater, 
altogether, than that of the frontals. The conspicuous temporal fossa runs round 
them, on the side and behind, up to the large triangular wedge of bone that shortens 
the sagittal suture and separates the two bones from the supraoccipital ; this triangle 
of bone is the interparietal (7.p.). 
Laterally, the premaxillaries, maxillaries, lachrymals, jugals, and squamosals ( pa., 
m., 1., 7.. sg.) can be seen flanking the great, gently convex, pyriform roof; all these 
are better seen, however, in the side view (fig. 3). 
Here we find that the premaxillary ( px.) is one-fourth the length, and one-half the 
greatest height, of the maxillary (mz.); its facial plate, thus seen, is notched in front, 
where it embraces the snout, and behind, when it is dinted by the maxillary ; above, 
instead of wedging in between the nasal and maxillary, it is actually rounded off. 
The maxillary is swollen in front where it runs against the premaxillary; above, 
where it runs up to the frontal, still more; and below, under the lachrymal and 
jugal bones (2, 7.). That Jast swelling is the outer alveolar wall of the last tooth, 
2 
. 
and above it there is a large and deep fossa for the maxillary nerve (V*.), but this 
* Whilst very grateful for what the Zoologists send me, I feel no ways bound to their groupings of 
the types. Their zeal for Taxonomy is not always according to knowledge, and by their hard and fast 
lines they often put asunder what Nature has joined, and leave together types that are not closely 
related, but merely mimetic, or isomorphie. 
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