108 MR. W. K. PARKER ON THE STRUCTURE AND 
good normal Mammalian character. The concave hind margin of the basioccipital (b.0.) 
is seen in the distance. 
The ossicula audittis (Plate 15, fig. 4) are, like those of the Armadillos (Plate 6, 
fig. 6 and 11; and Plate 7, fig. 6), intermediate between those of the more aberrant 
Edentates and those of ordinary Eutheria. 
Already in this relatively, and really very large, embryo, these parts are well formed, 
and the rest of the primary jaw is gone. The inner view (Plate 15, fig. 4) shows a 
reniform sinuous condyle, on a large head, which is convex externally, and scooped on 
the inside. The large styliform processus gracilis (p.gr.) is a little longer than the 
styliform manubrium (m.ml.), which is still cartilaginous. Doray’s figure (op. cit., 
Plate 64, fig. 14) shows a still smaller manubrium and a still larger processus gracilis, 
even in the adult. 
The quite normal incus (7.) is ossified, but the stapes (st.) has it facet and neck 
still cartilaginous ; in the adult (Doran, op. cit.) the long crus of the incus has become 
slenderer and the hole through the high stapes somewhat larger, and more circular. 
I see no interhyal nucleus in the tendon of the stapedius muscle (st.m.). One more 
point may be noticed, namely, that the base of the stapes is convex, and projects 
inwards beyond the rim, as in the Mole (Talpa europea), but not to the same 
extent. 
In the lower view of the peeled inner skull (Plate 15, fig. 1), the eye is almost con- 
fused with the number of parts to be described. If these figures be compared with 
figures already given by me in other papers of the endocranium,—of Selachians 
(Trans. Zool. Soc., vol. x., plates 34-42), and of the larvee of the Urodela and Anura 
(Phil. Trans., 1877, Plates 21-29; Phil. Trans., 1876, Plates 54-62 ; and «hid., 1881, 
Plates 1-44 ; Linn. Trans., ser. 2., Zool., vol. i, plates 14-21)-—it will be seen that 
the interpretation of the Mammalian skull is no easy task. But there lie, obliquely 
between this marvellously specialized skull and the skull of the Ichthyopsida, the 
various kinds of skulls to be seen in the oviparous “ Amniota,” or Sauropsida. 
To see the meaning of what les before me, here, in the skull of this somewhat 
abnormal, low Eutherian, I find it necessary to remember the structure of the skull 
in every division of the great groups just mentioned, that is in Serpents, Lizards, 
Tortoises, Crocodiles, and Birds. 
But the best of all these is the Crocodile, an ancient type, and one on which the 
loss of parts by degenerative specialization, is much less than in the other Sauropsida, 
for the living members of those other groups are manifestly more modified than the 
Crocodile.* 
This lower view (Plate 15, fig. 1) shows, behind the exposed part of the snout 
* Now, and for the future, I must avoid the use of the term Reptilian, qualifying it by the prefix qguasi,— 
for what islow in a Mammalian skull; if some Paleontologist were to stumble upon a fossil Hypotherian 
it would be a great gift of fortune, then one could use that term as an adjective. That such a type 
once existed I feel certain—as certainas that T myself have had a series of ancestors. 
