ZOOLOGY. 239 
8. Critical Remarks on the System. 
1. In the “ Transactions of the American Philosophical Society,” 
1869, part I. (August), I proposed a system in which the primary 
groups of the Reptilia were defined anew, and understood in some 
measure differently from those proposed by Owen. The system of 
the latter author, and that of Von Meyer, were the only ones ex- 
tant previously; and additional discovery necessitated some modi- 
fications, while the meritorious portions of both it was intended to 
‘preserve. The groups, perhaps equivalent to “orders,” retained, 
were the Ichthyopterygia, Archosauria, Testudinata, Pterosauria, 
Lacertilia, Pythonomorpha, and Ophidia. The form of attachment 
of the quadrate bone was regarded, after Johannes Miiller, as an 
element of prime importance in the estimate of affinities, and of 
nearly equal value, the differentiation of distal elements of limbs, 
the opisthotic bone, the mode of attachment of ribs, etc. 
Another systematic grouping of the orders was proposed by 
' Professor Huxley in the “Journal of the Geological Society,” 
London, 1869 (November), in which the position and character of 
the rib articulations to the vertebral centra were used exclusively 
in discrimination of the groups. The subclasses proposed were 
the Suchospondylia, which is our Archosauria; the Perospondylia, 
our Ichthyopterygia ;* the Herpetospondylia, corresponding to our 
orders Ophidia, Pythonomorpha, Lacertilia, with the addition of 
the Sauropterygia. The last group is rendered unnatural by the 
presence of the latter order, which possesses the closely articulated 
quadrate bone of the Archosauria. I therefore omit it, and retain 
the three orders remaining, in one division, which has already been 
named by Miller the Streptostylica. _Huxley’s fourth subclass, 
the Pleurospondylia, includes the Testudinata only. This group I 
also recognized in the original memoir quoted, and I accept it with 
* Some criticisms of Professor Huxley’s in this essay, on my determination 
of the structures and relations of the Dinosauria, are so inapposite as to require 
notice. He quotes me as saying of the astragalus of Lzlaps, that “one other 
example of this structure is known in the Vertebrata;” and adds, “but I shall 
show immediately: that the astragalus is altogether similar in the commonest 
birds, and probably in the whole class Aves.” This statement is so precisely the 
reverse of the fact, that I can only suppose it to be an inadvertence, or a double en- 
tendre, the latter being an impossibility in so fair a man as Professor Huxley. On 
page 85 he says: “ Professor Cope has distinguished Compsognathus as the type 
of a division Ornithopoda, from the rest of the Dinosauria, which he terms Goni- 
opoda, (on the structure of the foot, etc.)... It seems to me precisely by the struc- 
ture of the foot that Compsognathus is united with, instead of being separated from, 
