No. 377] THE ORIGIN OF THE MAMMALIA. 311 
This amphibian hypothesis has recently been supported by 
Hubrecht (1896), who upon embryological grounds specifically 
connects the mammals with the stegocephalian Amphibia. 
He concludes his very interesting and suggestive lecture, “ The Descent 
of the Primates,” by the passage (p. 31): “In fact, there is really not one 
potent reason which would prevent us from deriving arrangements, as we 
find fhenr: in the placental mammals, directly from viviparous PE 
ancestors.” Again (p. 37): “ My own choice is fixed upon the latter 
ae because in the Amphibia, from which I suppose tis Re 
placental mammals to have been derived, we find arrangements that appear 
to explain the origin of the amnion in the way here advocated.” 
There are numerous structures in the soft anatomy, not only of the 
monotremes, but of the placentals, which recall the amphibian type. Beddard 
has demonstrated the existence of an anterior abdominal vein in the mono- 
tremes. Howes! has compared the amphibian epiglottis with that of the 
mammals. Hubrecht? directs our attention to Klaatsch’s ® comparison of 
the close relations existing between the intestinal arteries of mammals and 
the most primitive arrangements of these vessels among amphibians. Else- 
where Hubrecht (of. cit.) declares that the mammals must be connected with 
very primitive forms that have already diverged from the common stem of 
the Chordata below the point of divergence of the amphibians now living, 
or, as we should add, from the stegocephalian type. Maurer * concludes 
that in the epidermal sense organs and hairs the mammals diverge consid- 
erably from the Sauropsida. 
Cope, on the other hand, in 1884, derived the mammals from 
carnivorous reptiles of the group Therontorpha and order 
Pelycosauria. 
Li 
Professor Cope, upon discovering the foot of the pelycosaurs with its 
supposed posterior spur, compared it with that of the monotremes, and 
hastened to the conclusion that these animals stood very near the ancestors 
of the mammals. He was long on record as deriving the Reptilia from the 
Batrachia with edolomerous (rather than rachitomous) vertebra, and from 
the pelycosaurian Reptilia, the Mammalia. In his Primary Factors of 
Organic Evolution, 1896, he writes: “ I have traced the origin of the mam- 
mal to theromorous reptiles of the Permian.” In this latest expression of 
his opinion upon the subject, however, he divided the Theromora into 
Theriodontia, Pelycosauria, and Anomodontia, and upon the opposite page 
1G. pete Proc. Zool. Soc. of London, 1887, p. 50. 
2 Op. cit., p. 38. 
"H Ea Zur Morphologie der Mesenterialbildungen am Darmcanal der 
TORE Morph. Jahrb., Bd. xviii, Sec. 643. 
+t F. Maurer, Morph. Jahrb., Bd. xviii. 
+ 
