608 REPORT—-1904. 
They applied to different periods in the history of the horse by different methods, 
which nevertheless promised to ultimately form points of contact and close up the 
wide gap which at present existed between the fossil, the historic, and the recent 
races of horses. Three years ago the American Museum began especial explora- 
tion into the fossil history of the horse, aided by a liberal gift from the Hon. 
William C. Whitney, former Secretary of the Navy. The object was to connect 
all the links between the Lower Eocene five-toed and Lower Pleistocene one-toed 
horses, and ascertain the relations of the latter to the horses, asses, and zebras of 
Eurasia and Africa. The first great result obtained is the proof of the multiple 
nature of horse evolution during the American Oligocene and Miccene. Instead 
of. a single series, as formerly supposed, there are five, one leading to Neohipparion, 
the most specialised antelope-like horse which has ever been found; a second of 
intermediate form, probably leading through Protohippus to Equus, as Leidy and 
Marsh supposed; a third leading to the Upper Miocene Hypohippus, a persistently 
primitive, probably forest- or swamp-living horse, with short crowned teeth, 
adapted to browsing rather than grazing, and three spreading toes; this horse 
has recently been found in China also. A fourth and fifth line of Oligocene- 
Miocene horses became early extinct. This polyphyletic or multiple law is quite 
in harmony with the multiple origin of the historic and recent races of horses, as 
recently established by Ridgeway and Kwart. The Pliocene horse of America 
still requires further exploration before we can positively affirm either that all the 
links to Equus are complete, or that America is indubitably the source of this 
genus. The Lower Pleistocene of America exhibits a great variety of races, 
ranging in size from horses far more diminutive than the smallest Shetland to 
those exceeding the very largest modern draught breeds; yet all these races 
became extinct, not surviving into the human period, as was the case in South 
America, The relations of these North American races to those of South America 
and of Asia and Africa is, again, a subject requiring further investigation, in which 
it is necessary to exercise the most extreme accuracy. Correspondence and 
interchange of specimens with other museums is greatly desired. 
The paper was illustrated by photographs of a large series of models of 
osteological preparations, showing the mechanism and breeds of the horse, and of the 
mounted fossil specimens recently discovered by the Whitney exploring parties. 
&. The Histogenesis of the Blood of the Larva of Lepidosiren.! 
By Dr, T. H. Bryce, 
9. The Hatching of Anuran Tadpoles. By HE. J. Burs, WA. 
WEDNESDAY, AUGUST 24. 
The following Papers were read :— 
1. The Effects Produced by Growing Frog Embryos in Salt and 
other Solutions.» By J. W. JENwINSON. 
2. On the Pacific, Atlantic, Japanese, and other ‘ Palolos.’ 
By Professor McInrosn, /.L.S. 
The forms included in these remarks belong to the pelagic fauna, a term 
more complex than is usually supposed, for it comprises two distinct series, viz., 
1 Will be published by the Royal Society of Edinburgh. 
2 Embodied in the Report on the Influence of Salt and other Solutions on the 
Development of the Frog (p. 288). 
