666 
ME. W. K. PAEKEE ON THE STETJCTUEE AND 
supposed to be segmented off from that adhering half-bar, is seen now to become the 
cartilaginous ear-ring. 
The important discovery, by Professor Huxley, of the late appearance of the “ colu- 
mella ” was extremely confusing to me at first ; it is now used as a key to unlock the 
most difficult “ wards ” of these organisms. 
It is evident that we have in the Batrachian hyoid arch that which lays its hand, as 
it were, upon the hyoid arch of both Fish and Mammal, and will soon explain both. 
Although the stapes is not segmented out from the ear-capsule of the “ Anura” (though 
it is so formed in the “ Urodela,” but formed later), yet it is periotic in nature, a hyper- 
trophied and chondrified tract of the perichondrium of the auditory cartilaginous wall, 
just where that wall thins itself and opens towards the vestibule. 
It appears to me that Dactylethra and Pipa, and even the Common Toad, by not 
cutting off the “interstapedial” as a distinct cartilaginous segment, but merely differencing 
it as a large, even the larger , shaft-bone, have shown that their “ columella ” is made up 
of a proximal “ hyomandibular ” and a distal “ symplectic.” 
The ultimate disposal of the large cartilages of the suctorial mouth of the Tadpole 
(the “ labials ”) has made the interpretation of the nasal capsule easy ; we now know 
what has budded out from the trabeculae (there are no distinct “ paraneural ” cartilages 
to the nasal sacs in the Anura), and what has been superadded to the labyrinth by the 
cartilages of the oral ring, in their metamorphoses. 
Now that we know the structure of the cartilaginous skull when it is first fairly a 
“ chondrocranium,” and that the two myotomic masses are not accompanied at first hy 
paraneural cartilages, but that the apices of the trabeculae cling to the apex of the 
notochord, distinct at first, and afterwards becoming confluent with the “ paraneurals ” — 
all these things, being true, will lead to further truth. 
Some of these things were seen by Professor Huxley long ago in the Newt, and lately 
in the Axolotl ; and by me afterwards, as the result of the most difficult demonstration 
ever made by me in the early larva of the Common Toad. 
Finally I may remark that not “ old experience,” only, is helping us, but new and 
more delicate means and appliances in our method of research. 
Description of the Plates. 
PLATE 54. 
Pan a temporaria. — Adult. 
Fig. 1. Fore part of endocranium (partially ossified chondrocranium), seen from above. 
X6 diameters. 
Fig. 2. The same, lower view. x6 diameters. (In this and the next figure the outer 
bones are faintly shown.) 
