ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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Pleurochondrite, cartilaginous, Pleurosteite, bony, elements of a rib, 
or autogenous transverse process. 
Prochordal plate, the middle trabecula of Rathke ; a mass of blas- 
tema formed above the upturned anterior end of the notochord, and 
continuous behind with the paracliordals. 
Prochordal cartilage, a nodular cbondrite which appears in the pro- 
chordal plate and gives rise to the mediodorsal portion of the dorsum sell®. 
On the whole, Prof. Parker inclines to the view that the Ratitfe are 
the descendants of birds which possessed the power of flight, and that 
they sprang from a “ protocarinate ” stock. On the hypothesis of its 
development from an ordinary reptilian fore-limb, the wing is one of 
the most striking examples of the uselessness of incident structures. 
Embryology of American Alligator.* — Mr. S. F. Clarke finds that 
the American Alligator deposits about thirty eggs in large nests close 
to a stream or pool. On each egg, soon after it is laid, there appears 
a transverse median zone which has a more chalk-white colour than the 
rest. This change is mainly due to a change in the shell-membrane. 
At first the embryo usually lies towards one pole of the egg. where it 
has the protection of the large mass of thick white ; later on, when more 
perfect respiration is needed, it moves over to a lateral position. 
The anterior or cephalic portion of the neural folds is formed by a 
median backward folding on the dorsal side of a thickened part of the 
head-fold ; this median fold separates at its apex, and each arm unites 
with the medullary fold of its respective side. The intestine passes out 
of the body to become attached to the yolk-sac. The pharyngeal clefts 
are five, and the first three become open to the exterior. The anterior 
one appears first as an internal groove lined by thickened epithelium ; 
this groove extends backwards and enlarges dorso-vontrally into the 
second cleft, and, in like manner, growing backwards, gives rise to the 
remaining three. All traces of the groove between the clefts soon 
disappear. 
Life-history of Vermilion-spotted Newt.j — Prof. S. H. Gaze gives 
an account of the remarkable life-history of Diemyctylus vivid escem. 
The ova are laid in water, and give rise to larvae with well-developed 
gills ; in the course of development these larvae take on the general 
viridescent colour of the adult. The gills are absorbed, the coloration 
changes somewhat, the oral epithelium becomes ciliated, and the respira- 
tion and life become wholly terrestrial. In two or three years the newt 
loses its red colour and becomes again viridescent, returns to the water, 
loses its ciliated and reacquires a stratified non-ciliated oral epithelium, 
and during the remainder of its life is properly an aquatic form. 
Tadpoles of European Batrachians.f — Mr. G. A. Boulenger gives 
an interesting account of the tadpoles of European Batrachians, in which 
he gives a key by which the eight genera and nineteen species may be 
distinguished. The longest known European tadpole is that of Pelobates 
fuscus, which measures 175 mm., and the shortest that of Bufo calamita, 
which is only 30. 
* Journ. of Morphology, v. (1891) pp. 181-214 (5 pis.). 
t Amer. Nat., 1891, pp. 1084-1110 (1 pi.). 
J Proc. Znol. Boe. London, 1891 (1892) pp. 59:4-627 (3 pis.). 
