182 PROCEEDINGS OF THE ACADEMY OF 



marked by more or less free leaves. Thuja ericoides of gardens, with its heath- 

 like foliage, was a weakly constituted form, which retained its childhood foliage, 

 and had little disposition to branch. Thuja meldensis of Lindley, which from 

 its peculiar appearance that learned author supposed to be a hybrid between 

 the red cedar and Chinese arbor vitro, was a form of intermediate vigor, 

 branching moderately, and leaves intermediately adnate. Retinispora ericoides 

 of Zucoarini, was also a weak form with free leaves, the well developed form 

 of which he had had no opportunity to trace with certainty. Taxodium dis- 

 tichum Richard, and Glypioslrobus sinensis Ya\A\., were no doubt the same thing. 

 He showed, by the vigorous branching character of the latter, the necessity 

 for the arrested foliation it presented, and exhibited specimens of vigorous 

 (more branching) Taxodium distichum in which the leaves were abbreviated 

 and twisted around the stem, exactly as in Glyptostrohus, except that the free 

 parts were rather longer. This form did not branch quite as much as the typical 

 Gli/ptostrobuSj but more so than in the typical Taxodium. 



He remarked that the two genera Finns and Sciodopitys had their true leaves 

 adpressed almost entirely to their branches, and illustrated this by specimens 

 oi Pinus austriaca. Histead, however, of these genera developing green free 

 points on the apices, they pushed out rather abortive branches from the axils 

 of the true leaves. The fasicles of leaves on these plants were not true leaves, 

 but were intimately connected with the axial system of the plants. The 

 adpressed true leaves on the pine were annual, although as dead epidermis 

 they remained often on the bark until the regular excorticating period arrived ; 

 but these so-called leaves, or rather metamorphosed branchlets, remained often 

 several years. He had known some remain eight years. Their connection 

 with the axial system could be seen by raising the bark of a three or four 

 year old branch on the Austrian pine. 



Mr. Gabb made some remarks about Kitchen Middens, in the vicinity of San 

 Francisco and on the shores of San Francisco Bay, his attention having been 

 called to the similarity between them and those observed by Dr. Leidy, near 

 Cape Henlopen. He also mentioned a curious circumstance for which he had 

 been unable to account. In various places on the coast of both Upper and 

 Lower California, he had observed shells, often of the heavier species, scattered 

 over the surface in great profusion, and occasionally to a distance of several 

 miles from the beach. They were evidently of very modern origin, being 

 strewn on the surface of the soil, but whether ihey had been carried there by 

 man or birds, he had never been able to discover. 



Dr. Wm. L. Wells made some observations on the mode of scattering the 

 ' spores of the Polypodium vulgare. Under the microscope the sporangium could 

 be seen to open at a point near its stem; and the opening grew very slowly 

 larger, until the continuation of the stem which previously encircled the 

 sporangium was nearly straight. It then suddenly sprang shut with a jerk, 

 which scattered the spores in every direction, and which usually sent the 

 sporangium itself out of focus. In the cases in which it was not thrown 

 entirely out of focus, the same operation could be seen to be repeated two or 

 three times. In no case were any spores scattered during the opening, which 

 always took place very slowly. 



July 21 si. 

 The President, Dr. Hays, in the Chair. 

 Fourteen members present. 



The following paper was presented for publication : 



" On the Crocodilian genus Perosuchus." By Edw. D. Cope. 



[July, 



