GIG MR. W. K. PARKER OK THE STRUCTURE AND 
The concavity of the lower jaw is shallow and sinuous; the articulare has a con¬ 
siderable angular process, and the bone itself is seen most on the inside (Plate 43, 
fig. 2, ar.) ; Meckel’s cartilage is reduced to small dimensions within the splints. 
The other post-oral bars are very slender (Plate 42, fig. 5), the stylo-ceratohyal 
(st.h., c.hy.) runs up to the side of the ear-capsule, just below the fenestra (Plate 45, 
fig. 6, st.h.), and then passing downwards and forwards, it enlarges into an ear-shaped 
lobe in the cerato-hyal region. 
The hypohyal ( h.liy .) is short, and turns suddenly backwards; where it articulates 
with the basihyal ( h.liy .) that bar is wide and shows no separate joint behind this 
articulation; the rest of the median rod is very long and slender : it is the skeleton of 
the protrusible tongue. 
Both the hypohyals and first branchial bars (hr. 1 ) are scarcely distinct from the 
basal piece ; the latter are long and elegantly sigmoid with the distal three-fifths ossified, 
and the proximal part pointed and turned inward. 
Another bar, half as long as the first, and unossified, lies behind the first branchial 
above; it is /-shaped, with the top hooked inwards, like the lower piece ; this is the 
upper (br.~), or “ epibranchial ” part; it has a small snag outside its middle. 
Besides this, there is on each side, a slender, slightly outbent hypo-branchial (k.br.), 
this belongs to the second branchial, and also from its length is evidently part of the 
third, neither of which cliondrify, above, in the embryo/ 1 ' 
First Stage. Embryos of Lacerta agilis 2| lines (\tli of an inch ) long, measured along 
their curve. 
To prevent misconception as to size, I may mention that the embryos of large types 
of any class are much smaller, relatively, than those of small species. 
For instance, my third stage of this minute species corresponds exactly to young 
embryos, in my possession, of the Green Turtle (Chelone viridis) ; these are only 
half an inch long, whilst those of Lacerta agilis measure five-twelfths (5 lines); thus 
they are only one-twelfth of an inch shorter than the embryos of that gigantic Reptile. 
Again, the embryos of the Common Pig, figured in my paper in the Philosophical 
Transactions for 1874 (Plate 28, figs. 1-3), scarcely measured two-thirds of an inch, 
whilst similar embryos of the Common Mole (Talpa Europccafi are three-fourths of that 
length, namely, about half an inch. 
Another thing to be noted is this : that in both those cases, the Turtle and the Mole, 
these, my younger specimens, can be seen to belong to those types ; the embryos of the 
* So that we are but just escaping from tlie branchiate Vertebrata; the Pipa Toad —with its four 
“ extra-branchial ” bars, and branchias so fugacious that my early embryos (“ Skull of Batrachia,” Part I., 
Plate 60, figs. 1, 2) had lost them—is an outsider of the “ Branchiataand this little, highly-meta¬ 
morphosed Lizard, has scarcely thrown aside the skeleton of these organs of aquatic respiration. 
f The gift (with several other stages) of T. Southwell, Esq., of Norwich. 
