106 REPORT—1862. 
aspect. That condition is only found in the tail; and the tail is not a typical por- 
tion of the body, but a degenerated series of segments, in which the products of the 
deepest parts of the embryo are entirely unrepresented. 
With regard to the series of structures traced back into the tail, it was shown that 
structures lying in series were not necessarily strictly homologous, that, in fact, 
correspondence was a thing of degree, and that inferior arches of caudal vertebrae 
were found in series sometimes with mesial spines, sometimes with vessel-embracing 
arches, sometimes with costal arches of trunk-vertebrae, and sometimes with more 
than one of these. The key to the comprehension of the skeleton was maintained. 
to lie in the double relation of the skeleton of the trunk to the visceral cavity and 
chorda dorsalis, both being to it centres, but in different senses—the visceral cavity 
being that which it tended to encircle, the chorda dorsalis the line from which its 
efforts to encircle the visceral cavity began. 
The correspondence of inferior caudal arches of one class of Vertebrata to those 
of other classes was shown to be of primary importance ; and their differences in 
respect of attachment, and of the structures with which they were in series, of 
secondary importance. 
All transverse processes or ribs tending to embrace the visceral cavity were 
shown to have a primary correspondence, even though attached to different parts of 
the vertebrae, and to be more closely allied one with another than to any structure 
Sea into the muscles, such as the superior transverse processes and ribs of 
fishes. (This paper is published in full in the ‘Nat. Hist. Review’ for Jan. 1863.) 
On Geoffroy St.-Hilaire’s Distinction between Catarrhine and Platyrrhine 
Quadrumana. By Dr. Cortrnewoon, Liverpool. 
The terms applied long since by this eminent French naturalist are of great 
general importance, and point out very characteristic distinctions; but the defini- 
tions universally given of those terms are such as to make the terms themselves 
appear liable to numerous exceptions. Thus, the Old-World Monkeys — 
nasal septa varying from } inch (Semnopithecus) to 3 inch in thickness (Colobus) ; 
while in those of the New World, although the septum is sometimes (Cebus) 
8 inch thick, in other instances it does not exceed 4 inch (Eriodes). Neither 
do the definitions “nostrils opening beneath (or in front of) the nose,” and 
“nostrils opening to the side of the nose,” apply by any means generally. It 
appears as though the spirit of St.-Hilaire’s distinctions were quite forgotten by 
his successors, who have endeavoured to connect all the Quadrumana under a 
Procrustean rule. Typical animals fulfil, for the most part, the definitions given ; 
but aberrant genera wander in this respect, as in others, from the ordinary defini- 
tions. It is to the form of the septum itself, in its anterior aspect, that we must 
look for the real basis of St.-Hilaire’s distinctions—that form being wedge-shaped 
in the Monkeys of the Old World, and hourglass-shaped in those of the American 
continent. This causes all the curious changes of direction which the nostrils 
undergo, and is without exception. Hence it results that in Catarrhine Quadru- 
mana the lower angles of the nostrils rapidly converge over the mouth, while those 
of the Platyrrhine Monkeys diverge—a test which, while it is most readily applied 
and is not liable to misinterpretation, is at the same time altogether independent 
of the thickness of the nasal septum. 
An the Change of Form of the Head of Crocodiles ; and on the Crocodiles of 
India and Africa. By Dr. J. E. Gray, FBS. 
The author stated that the Crocodile, when first hatched, has the front of the face 
short and rounded, even in those that have an elongated beak in the adult state. The 
nose of the different species lengthens, and gradually assumes the form which is the 
character of the kind; and it is at this age that the peculiar forms of the different 
kinds are best examined and compared. After the animal has assumed its adult 
size, the bones of the head dilate on the side, and the forehead and nose become 
more swollen. The change of form thus produced is so great, that some naturalists 
have regarded them as distinct species. This dilatation of the sides and increase in 
