NATURAL SCIENCES OF PHILADELPHIA. 181 



E. D. Cope exhibited the vertebra of an extinct reptile, from tlie middle green 

 sand bed of New Jersey ; which possessed the peculiar articular structure known 

 as the zjgantrum and zjgosphen. He said the form was in some degree like that 

 of certain modern terrestrial genera of Iguanida;, as the genus Euphryne, 

 Baird, but it appeared to have some affinity to Macrosaurus, Owen, in form. 

 The animals, if similar in proportions to the Iguana^, would have been some 

 twelve feet in length. It was called Clidastes iguanavus. 



A Mosasauroid reptile was indicated also by a single vertebra from Medford, 

 N. J., also from the middle bed. It was distinguished from other forms of the 

 family by its compressed elevated form. It was assigned to a species named 

 Nectopohtheus validus. 



The structure of the vertebral column in Elasmosaurus was pointed out. It 

 was stated to possess apparently no zygapophyses throughout its whole length, 

 but in place of these, the zygosphen and zygantrum articulation. The articu- 

 lations of the vertebras were therefore the reverse, in respect to direction of 

 their surfaces from the usual form among vertebrata. In fact the structure of 

 the genus was shown to be entirely new and peculiar among vertebrated 

 animals. The genus Cimoliasaurus, Leidy, was stated to exhibit the same 

 structure, and required that the vertebraj should be reversed in order to read 

 their connections correctly. 



Thomas Meehan said he had proposed to himself to contribute a paper to 

 the American Academ}"- of Science which meets next month in Chicago, on the 

 leaves of Coniferai : but some friends here acquainted with his intention, and 

 interested in the facts, were desirous he should explain to them some of the 

 leading points, which he would with pleasure do. 



His chief position was that what are usually considered the leaves of Coni- 

 ferse are but a part, and frequently the least important part of the true leaves, 

 which are either mostly adherent or mostly free according to the vigor of the 

 branch or individual plant, and not according to any specifically constitutional 

 character ; and that a recognition of this fact is of great importance in deter- 

 mining the limits of genera, species and varieties of the Order. He exhibited 

 specimens of the Lariz Europoea, pointing out that it had two classes of leaves, 

 tlie one entirely free, the other mostly adnate to the stems. The adnate leaves 

 were on the elongated shoots, the free leaves on the arrested shoots or verti- 

 cills ; on the elongated shoots the leaves also had a power of elongation, 

 and produced the green awl-shaped points we commonly called leaves. On 

 the arrested shoots or spurs, the leaves had no power of elongation. They 

 were obtuse, rather spatulate, just the same as the adnate portion — the true 

 leaves — on the stem. The theory he deduced from this was that adnatwii u-as a 

 characteristic of vigor ; free leaves a condition of toeakness or arrested growth. This 

 explained the polymorphous character of manj' Conifera". The rule operated 

 through many genera. He exhibited strong branches of Cryptomeria japonica, 

 on which the leaves were united for four-fifths their length, and weaker ones 

 on which four-fifths were free, &c. The same occurs on Juniperus viryiniana, 

 Juniperus conwiunis, Thuja orientalis, T. occidentalis, and other species. Wher- 

 ever the shoots were delicate, either constitutionally or by growing in the 

 interior of the plant and deprived of their due share of light, the leaves were 

 free ; wherever the contrary existed, and the shoots were vigorous, aduation in 

 a greater or less degree prevailed. In many species this polymorphous condi- 

 tion could be produced at will, by weakening the plant. Cuttings of Thiijopsis 

 borealis made from branches with adnate leaves, would throw out shoots with 

 free leaves until they were very well rooted and able to throw out vigorous 

 shoots. 



A test of vigor was the power to branch. Only on vigorous maturity did the 

 branching age of trees commence. Arbor vita?s, when mature, i)ushed out 

 branches from the axils of every other pair of leaves. This gave them their fan- 

 like appearance. When young they branched little, and tliis stage was always 



1868.] 



