DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 
653 
On the Skull of Pipa monstrosa. — Second Stage. Ripe young , to lines in length . 
In this stage all the figures except one (Plate 60. fig. 7, the mandible and brancliials) 
are from young that were showing their faces at the mouths of the dorsal pouches ; these 
were 7^ lines, or nearly two thirds of an inch, in length. The others were still rolled 
up and were slightly above half an inch, in length. Yet these unawakened larvae were 
perfectly metamorphosed, and I could see no difference whatever, even in the degree of 
their ossification, which was intense, and far beyond what I expected to find in such 
small young of so large a species. Now in the earliest stage I have (Plate 60. figs. 1, 2) 
the entire length was 9 lines, nearly half the length being due to the tail ; therefore it 
is seen that when metamorphosis is perfect the body is only one fourth of an inch longer 
than it was at the time that the yelk-mass was but little lessened in substance (not at 
all in size), and that the series of somatomes perfect themselves into the body, vertebrae, 
muscles, &c., by filling in, as it were, the original map, and scarcely modifying the 
size of the territories. Also it may be remarked that the head of the early embryo 
(Plate 60. figs. 1, 2) is two lines, or one sixth of an inch, in length, the condition of whose 
skull has just been described (Plate 60. fig. 3) ; whilst the head of the unrolled young 
is three lines long. Thus it is seen that the lengths are (without the tail) as follows : — 
Early embryo : head ^ inch, body ^ inch ; total inch. Ripe young : head \ inch, 
body inch ; total fz inch (taking the average of the two sizes of the young Pipes). 
The figures of the chondrocranium (Plate 60. figs. 3, 5, 6), the degree to which 
they have been magnified being considered, show how much the metamorphic action 
has modified the condition, and how little the size ; a like case to that with which all 
are familiar, namely, during the “ vernation ” of trees ( e . g. of PEsculus), when the new 
internode gains its length in three or four weeks, and takes the rest of the season to 
stiffen itself by deposit*. 
The unexpected finish of these ripe, or nearly ripe, young Pipce makes it necessary to 
modify, a little, my mode of illustration. The figures of the chondrocranium at this 
stage (Plate 60. figs. 5, 6) are made by drawing the still existent cartilage, and leaving 
out in those figures the ectosteal deposits (see, in contrast, Plate 61. figs. 2, 3). 
And here is another anomaly, namely, that whilst the cartilage has been used up in 
the auditory capsules, leaving large spaces, above and below, only invested by bone, the 
same thing, contrary to wont and experience, has taken place where the great para- 
sphenoid lies (Plate 60. fig. 6, and Plate 61. fig. 3 ; compare with these the adult Toad’s 
skull, Plate 54. fig. 4). Here the development of an underlying “ parostosis ” has been 
coupled with the absorption of the newer cartilage of the primary pituitary space (see 
Plate 55. fig. 1 ,pt.s.), which lies upon that splint-bone. Here, again, in a Batrachian we 
see the want of any proper boundary line between a parostosis and an ectostosis, the differ- 
ence between which is so clear in “ Teleostean ” Fishes, and the “ Sauropsida,” generally. 
Such a chondrocranium as we see here (Plate 60. figs. 5, 6) is a fair and clear diagram 
* There is a familiar instance nearer home, namely, in the almost completed length of the foal’s “metatarsus ” 
and “ metacarpus ” at the time of birth. 
