Makch 25, 1904.] 



SCIENCE. 



503 



in the publications of the Geological Survey 

 of that state. 



Mr. Ralph Arnold then presented a paper on 

 the ' Faunal Eelations of the Carrizo Creek 

 Beds of California.' He first described the 

 physiographic features of the Carrizo Creek 

 country, which lies in San Diego County on 

 the edge of the Colorado Desert near the Mex- 

 ican boundary line. The faunal relations of 

 the mollusks of the formation were next dis- 

 cussed. The moUuscan fauna indicates that 

 the Carrizo Creek beds are for the most part 

 of Miocene age, that they were laid down in 

 comparatively shallow water, and that their 

 fauna bears little relation to other known 

 California Miocene, but is intimately related 

 to the recent fauna of the Gulf of California. 

 These facts point to the conclusion that during 

 at least a part of the Miocene period the Car- 

 rizo Creek country was occupied by a tropical 

 shallow sea or gulf, an extension of what is 

 now the Gulf of California; and that this 

 gulf was separated from the cold waters of the 

 main California Miocene sea by a peninsula 

 similar in position to the present peninsula of 

 Lower California. In other words, he con- 

 cluded that the major physiographic features 

 in the peninsular and gulf region of Lower 

 California were approximately the same in 

 Miocene times as they are at present. 



This was followed by a paper by Mr. T. 

 "Wayland Vaughan, entitled 'A Calif ornian 

 Tertiary Coral Eeef and its Bearing on Amer- 

 ican Eecent Coral Faunas.' The coral reef, 

 concerning which he spoke, occurs in San 

 Diego, County, California, the locality being 

 the same as that of the Carrizo Creek beds 

 described in the preceding paper by Dr. 

 Arnold. Mr. Vaughan first called attention 

 to the striking difference between the recent 

 coral faunas on the Atlantic and Pacific sides 

 of subtropical America. 



In the collection that has so far been made 

 from the California fossil reef five genera are 

 represented, all of which occur in the fossil 

 and recent faunas of the Antilles and not one 

 of which is at present known to occur on the 

 Pacific coast. The age of the beds in which 

 these fossils occur has been determined by Drs. 

 Arnold and Dall to be Lower Miocene. The 



following coiiclusions seem warranted: (1) 

 There was water communication between the 

 Atlantic and Pacific across Central America 

 not much previous to the Upper Oligocene or 

 Lower Miocene, that is, during the Upper 

 Eocene or Lower Oligocene. This conclusion 

 is the same as that reached by Messrs. Hill 

 and Dall, theirs, however, being based upon a 

 study of the fossil mollusks. (2) During 

 Lower Miocene time the West Indian type of 

 coral fauna extended westward into the Pacific 

 and it was subsequent to that time that the 

 Pacific and Atlantic faunas have become so 

 markedly differentiated. 



Alfred H. Brooks, 



Secretary. 



NEW YORK ACADEMY OF SCIENCES. 

 SECTION OP BIOLOGY. 



At the February meeting the following 

 papers were presented : 



A New Gigantic Tortoise from the Miocene 



of Colorado: O. P. Hay. 



This tortoise was discovered during the year 

 1901 by Mr. Barnum Brown, of the American 

 Museum of Natural History, in the Pawnee 

 beds of the Miocene, in the northeastern part 

 of Colorado. The remains consist of the shell 

 complete; the skull, lacking the lower jaw; 

 the pelvis and hind limbs; the terminal por- 

 tion of the tail; and portions of the dermal 

 armor. These materials were exhibited before 

 the academy. 



The length of the carapace is about 31 

 inches. It is high and tumid, with the sides at 

 the bridge perpendicular, and with the hinder 

 border little fiaring. The outline is truncated 

 in front, broadly rounded behind, and only 

 slightly repand. The free edges are acute. 

 The bridge peripherals rise somewhat above 

 the middle of the height of the shell, their 

 length transversely to the animal being nearly 

 equal to that of the costal plates. The nuchal 

 scute is narrow; the vertebral scutes not so 

 wide as the costal scutes. The anterior lip 

 of the plastron is broad, rounded in front, and 

 slightly notched in the midline. The posterior 

 lobe has a broad, shallow notch. The pectoral 

 scutes are extremely narrow. 



