852 
cleate and more complex than fish-sperm chro- 
matin. Neither bull or pig sperm contain pro- 
tamin. The author suggests that the simplicity 
of fish-sperm chromatin is difficult to reconcile 
with Weismann’s hypothesis. 
Dr. Bashford Dean, in ‘ Notes on Palzos- 
pondylus,’ gave a brief reply to Dr. Traquair’s 
recent objections (Pro. Zool. Soc. Lond. March 
16, 1897). The author notes: 
(1) That the radial-shaped markings of the 
type specimen are certainly part of the fossil, 
since they occur in a second specimen now in 
the possession of Professor Stratford. 
(2) That his broader interpretation of the 
‘unpaired nasal opening’ (Traquair) as a naso- 
mouth ring (as in Myxine) was an independent 
as well as a necessary one, as will appear in the 
full paper. 
(38) That the view of the presence of the 
radial-shaped markings as the probable sup- 
ports of paired fins, the relations of Palwospon- 
dylus to the Marsipobranchs, become even more 
hypothetical. 
Dr. Matthew reported on the status of the 
Puerco fauna. A review of the Puerco fauna, 
based on Dr. Wortman’s geological observations 
in the field and the records kept by the Ameri- 
can Museum collecting parties, shows that the 
Upper and Lower Puerco beds do not contain 
a species in common, and only three or four 
genera pass through. The two faunas are en- 
tirely distinct. Dr. Wortman proposes to call 
the upper beds the Torregon formation, retain- 
ing the name Puerco for the lower beds. 
Mixodectes, formerly supposed to be a primate 
allied to the modern Chiromys, is a true Rodent 
in the first stage of evolution. It has the char- 
acteristic Rodent astragalus, very like that of 
the earlier Sciuromorphs. The incisor is inter- 
mediate between the short, rooted spatulate in- 
cisor of most modern mammals and the long, 
rootless scalpriform incisor of the Rodentia. 
The root is long, but does not grow from a per- 
sistent pulp, and the crownis long and pointed, 
but still retains much of the spatulate shape. 
The canine and anterior premolars are disap- 
pearing, the fourth premolar becoming molari- 
form, and the molars showing some traces of 
an impending change to a type like that of the 
Wasatch rodents. 
SCIENCE. 
[N. 8. Von. VI. No. 153. 
More complete material of many species 
shows that all the placental mammals were re- 
markably similar in skeleton structure. They 
were plantigrade, pentadactyl, with claws or 
narrow hoofs, short, clumsy limbs and long, 
heavy tail. Contrary to expectation, the podium 
and metapodium are not usually arranged in 
serial order. The carpus is alternating in the 
four species in which it is known, and the tarsus 
is serial in only two out of eleven species. Of 
these two, one is a primate, the other is the an- 
cestor of Phenacodus and has an alternating car- 
pus. The direct ancestors of the Perissodactyls 
and Artiodactyls do not seem to be among the 
known Basal Eocene species. The Creodont 
Clenodon resembles the modern bears in foot 
structure as well as in the teeth, and may have 
been ancestral to them. Considering that such 
widely different types as the Edentates, Ro- 
dents, Primates and Amblypods have been 
traced to their first beginnings in the Basal 
Eocene, it may be concluded that the first dif- 
ferentiation of all the Placental mammals took 
place at the beginning of the Tertiary and not 
in the Cretaceous as has frequently been stated. 
Dr. Matthews’ paper was discussed at length 
by Professor Osborn and Dr. Wortman. 
Mr. Harrington reported on some observa- 
tions which he had made on ‘Karth Worms 
during Copulation.’ He described an organ 
which apparently had been usually overlooked. 
This organ, the spermatophore of some authors, 
consists of a modified seta, much enlarged at 
the extremity and functioning, as Mr. Harring- 
ton suggests, to force spermatozoa into the 
seminal receptacles of the other worm. 
Gary N. CALKINS, 
Secretary of Section. 
THE ACADEMY OF SCIENCE OF ST. LOUIS. 
Atv the meeting of the Academy of St. Louis 
on the evening of November 15, 1897, Professor 
F. EB. Nipher presented informally some of the 
results of recent experiments on the stability of 
a pivotally mounted sheet in an air stream, his 
experiments having been performed by exposing 
the pressure planes on the roof of a moving box 
car. 
WILLIAM TRELEASE. 
Secretary. 
