654 The American Naturalist. [July, 
Natural History specimens. The Chair appointed Doctors Dyar and 
_ Dean and Prof. Stratford. 
Professor Bristol offerred his resignation as Secretary. It was 
accepted, and the election of his successor was laid over until the next 
meeting. 
Prof. Osborn reported upon the phylogeny of the early Eocene Tit- 
anotheres, showing that they are divided into two distinct series in- 
cluded under the genera Telmatotherium and Palosyops, both of 
which independently acquired horns. The Telmatothere line begins 
with T. boreale, a form which Cope referred to as Palzosyops. It is 
distinguished by animals with long narrow skulls and high stilted feet, 
and undoubtedly represented the upland types of the family. The 
Palzosyops line, as suggested by Earle and Hatcher, passes through P. 
laticeps and P. manteoceras and leads up to Dipladodon, the larger 
species of which surpass in size the smaller Titanotheres of the Oligo- 
cene. This main line gives off several collaterals, such as P. paludo- 
sus. Lambdotherium does not belong in the Titanothere phylum at 
all. 
A second note related to a division of the two groups of placental 
mammals, the Meseutheria and Ceneutheria. The former, since Wort- 
man’s demonstration that the Ganodonta are ancestral edentates, must 
now embrace this division, besides the Creodonta, Lemuroidea, Tillo- 
dontia, Insectivora, Amblypoda and Condylarthra. 
The third note related to the origin of the typical mammalian types 
of teeth among the Theriodonta, Cynodontia and Gomphodontia of the 
_ Triassic. It is especially noteworthy that the Gomphodontia afford a 
demonstration of the origin of Multituberculate teeth from a trituber- 
culate ground plan, as hypothetically assumed by the speaker some , 
years ago. 
Mr. Bradney B. Griffin reported that in Thalassema (one of the 
Echiurids) the spireme occurs in minute ova (3 micra in diameter) 
floating clusters in the body cavity. The spireme segments into one- 
half the somatic number of chromosomes, which by partial longitudinal 
splitting pass into flattened ellipses. These elongate, and during the 
growth period become twisted and distorted, and their true shape there- 
by obscured. While entering the first polar spindle they appear as 
loose open rings or compact rods (bivalent). These by concentration 
and looping-up form crosses, opposite arms of which are attached to the 
“ Zugfasern.” During metaphase the crosses become drawn out into 
flattened ellipses which split across into two V’s with closely apposed 
limbs. At telophase the latter separate at the angle and diverge in the 
second polar mitosis. No longitudinal splitting of the V’s occurs. 
