DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 
157 
Here, again, in the large bony inter-stapedial and the suppressed snpra-stapedial 
we have a curious mixture of what is arrested and over-developed. 
The mandibles (fig. 8) are well developed and quite normal, except that the articular 
condyle is very deeply sulcate, so as to be the exact reniform counterpart of the quad¬ 
rate condyle of other types; this is in conformity with the very deep scooping of the 
part on which it rolls (figs. 6 and 7, q.c.). 
The cerato-hyal band (fig. 8, c.liy.) and the hypo-hyal lobe (h.hy.) are quite normal, 
but the large front notch, as in the other kind (fig. 3), is unusually short. 
The whole plate is large, and here the lateral lobe is notched in front, is of large 
extent, and is only separated from the hinder small lobe by a gentle emargination, 
there is an approach to this in the other (fig. 3), but here (fig. 8) we have it well 
developed, and it is a rare condition. 
The thyro-hyals (fig. 8, t.hy.) are rather large and only moderately divergent, they 
show age in a remarkable w T ay; the inner edge of each is produced into a large wing 
of periosteal bone; moreover, the basal plate ( b.h.br .) is all converted into true bone, 
except at its edges. 
More or less calcification often occurs and is typical; sometimes true bone appears 
close to the thyrodiyals; here, however, the bony substance reaches to the front notch, 
and runs far into the lateral lobes. 
The investing bones are exactly such as we see in newly transformed Frogs of the 
common kind. The fronto-parietals ( fp .) are quite similar to those of the young 
Hylarana (figs. 1 and 2), and the nasals (■ n .) are small, crescentic shells, covering very 
little of the cartilage. The marginal bones ( px ,, rnx. , cpj., sq .) are frail splints, like the 
palatine and pterygoid ectostoses. The parasphenoid has similar wings to the other, 
and its main part is short but very broad ; here again we have the characters of a young 
Frog. The vomers (fig. 7, v.) are very minute toothless crescents, and there are no 
septo-maxillaries. 
Many of the characters of this dwarf are those of a young tyjjical Rana, but the 
intense ossification of certain regions show that it is an adult arrested at certain points. 
It differs from the “norma” in the following particulars :— 
1. The cranial notochord is large and persistent. 
2. The occipito-otic centres are arrested. 
3. There is only one, and that a very large, fontanelle. 
4. The mid and fore skull are very wide, and the latter has the roofs very tumid, 
as in young species of other kinds. 
5. There is a prenasal rostrum. 
6. The palato-suspensorial ectostoses are arrested. 
7. The quadrate condyle is of an unusual form, being deeply scooped, and its counter¬ 
part in the mandible being reniform with a very definite “ hilus.” 
8. The retention of the larval “ orbitar process.” 
9. The intense ossification of the inter- and the absence of the swpra-stapedial. 
