1877.] Proceedings of Societies. 255 
PROCEEDINGS OF SOCIETIES. 
Iowa ACADEMY OF Scrences.— October 6th. Professor Bessey 
read a paper on Some Observations upon the Growth of Plants, made 
by Means of Arc-Indicators. Professor Macomber read a paper on The 
Barometer as an Indicator of the Weather. A List of the Odonata of 
Central Iowa, prepared by Herbert Osborne, was communicated by the ` 
chairman. 
Professor Bessey read a paper entitled A Case of Selection, pointing 
out how the relative number of individual plants of blue-grass (Poa 
pratensis), white clover ( Trifolium repens), and Panicum glabrum changed 
under certain conditions, the first decreasing and the last two increas- 
ing under more frequent close cutting. 
Also, by the same, Observations on Silphium laciniatum, the so- 
called compass plant. About thirty per cent. of all the leaves of this 
plant do not deviate more than five degrees from due north; forty-two 
per cent. deviate less than ten degrees, and ninety per cent. deviate less 
than forty-five degrees, so that it fully deserves the common name of 
compass plant. 
ACADEMY or NATURAL Sciences, Philadelphia. — December 12th. 
Professor Cope exhibited a jaw-bone of a Dinosaurian reptile of the 
genus Lelaps, from the Judith River beds, and described its characters. 
It was said to be the most perfect specimen of the kind yet found, al- 
though the whole jaw was at least a foot longer than the specimen. He 
added three species of Lelaps to those already described from the Judith 
River beds, making six in all from that locality. Ten species of herbivo- 
Tous dinosaurs have been described from the same formation. He at first 
thought the specimen exhibited might be the Aublysodon horridus of 
Leidy, but the anterior teeth differ materially from those of the species , 
named. The name Lelaps incrassatus had been proposed by Professor 
Cope for the form some time since, on the evidence of a few teeth. 
A number of specimens of teeth of the other species of Lelaps and 
Aublysodon were shown and described. The Lelaps incrassatus is the 
gest species as yet found in the Western beds. A new genus, which 
was stated to be between the genera Paronychodon and Lelaps, was de- 
scribed under the name Zapsilus. 
Professor Cope also exhibited a cast of the interior of the cranium of 
ena forcipita. The anatomical peculiarities of the Creodonta ea 
dwelt upon in this connection. The form of the brain resembled mos 
nearly that of the opossum. - 
December 19th. Professor Cope exhibited a specimen of the cranium 
and some other bones of a fossil reptile of the genus Olidastes, in a single 
slab of the Cretaceous chalk which composes Cretaceous number three of 
the West. The specimen consists, in addition to the cranium, of the atlas 
And two of the cervical vertebra, the former exhibiting the four elements 
of which it is composed. 
