with the med m plane n the line of light, a 



to place the ventral or dorsal side towards th 



In an appendix certain interesting experii 



insects are communicated in addition to tho 



treating of heliotropism. That caterpillar: 



rapidly ascend vertical sides of hoxes and rei 



ascribed to a negative geotropism ; while th 



up by cockroaches, butterflies, spiders, etc., w 



orientation with reference to gravitation, din 



Most suggestive experiments in extension 



appears that insects in a centrifugal much 



too far from the main thesis. That the geotropism is not confined to 

 insects is well shown by Loeb 1 in the case of certain sea cucumbers 

 ' Cunimnria ritriuitit) which ascend to the top of an aquarium even 

 when the apparatus is so devised that there is no question of greater 

 air supply etc., at the top.— E. A. Andrews, Feb. 12, 1892. 



The Homologies of the Cranial Arches of the Reptilia.— 



The following paragraphs contain an abstract of a paper read before 

 the U. S. National Academy of Science under the above title on April 

 19th, and published in the Transactions of the American Philosophi- 

 cal Society in May, 1892. 



The paper recorded an analysis of the cranial characters of the 

 genera of Reptilia discovered in Permian beds in North America by 

 myself. Those especially studied are Pariotichus, Parity] us and 

 Chilonyx, which belong to the Cotylosauria (Cope; Pariaaanria 

 Seeley) ; and Edaphosaurus, Clepsydrops and Naosaurus, members of 

 the Pelycosauria (perhaps equal the Theriodonta of Owen) ; and 

 Diopeus g. n., founded on Clepsydrops leptocephahis Cope. The 

 < ''»tylosauria have the temporal fossae overroofed, so that the skull has 

 the general character of that of the Stegocephalous Batrachia, with 

 Which it also agrees in its segmentation, an agreement especially well 

 marked in Chilonyx. 



The hypothesis of Baur was tested in its application to the origin 

 of the bars of the Reptilian skull. This hypothesis supposes that the 

 bars have been derived from the Cotylosaurian roofed skull by perfor- 

 ation, a kind of natural trephining; the position of which has deter- 

 mined the position and constitution of the bars or remaining portions 



1 J. Loeb; Ueber Geotropismus dei Thiere. Arch. |. d. ges. Phys. xbx., 1891. 



