SUNKEN PACIFIC LAND 331 



since very remote geological times, while its ancient moun- 

 tain system, trending in a west- eastward direction, abruptly 

 terminates on the Pacific coast. I ventured to explain 

 the many instances of curiously discontinuous distribution 

 in Central America by the supposition that an ancient land 

 occupied the adjoining portion of the Pacific, and that the 

 present Central America is partly formed of the remnants of 

 that land having eventually become moulded together by geo- 

 logically recent volcanic deposits. If we assume that the Cape 

 Eegion of Lower California belonged to that Pacific land 

 which really formed the southern continuation of the north 

 Pacific belt of land alluded to, a reasonable explanation is 

 advanced for the faunistic affinity of the Cape Eegion to 

 Central America, the West Indies and Asia, and its dissimi- 

 larity with the rest of Lower California. The hypothesis of a 

 fortner westward continuation of portions of Central America 

 is not founded purely on zoogeographical considerations. 

 In his reference to the older Tertiary sediments of Central 

 America Professor Hill* states that it is impossible to avoid 

 the conclusion that they were derived from a near-by 

 land which existed at the time of their deposition. The only 

 hypothesis, he says, that can fit the condition of their 

 present lay and arrangement is that this land existed 

 towards the Pacific coast or in the area now covered by the 

 Pacific waters of the Isthmian Region. The " old land " 

 or early representative of the isthmus of Panama, remarks 

 Mr. Hershey,t lay mainly south of the present isthmus. 

 That it was a land-mass of considerable extent, he con- 

 tinues, is indicated by the heavy beds of conglomerate 

 formed from it, and he argues that the peninsula of Azuero 

 which projects out into the Pacific is a remnant of this land, 

 while on its northern border were laid down the more recent 

 formations which make up the main body of the isthmus. 

 Geologically there is, therefore, some evidence, too, for the 

 assumption of a former extensive land surface on the Pacific 

 side of Central America. It must be remembered that while 

 Central America as a whole has a south-east and north-west 



* Hill, E. T., " Geological History of Panama," p. 263. 



t Hershey, 0. H., " Geology of Isthmus of Panama," p. 249. 



