REVIEWS 757 



common than the Holothurians; a single new genus and species, Pey- 

 toia nathorsti, is described, its condition of preservation being identical 

 with that of the Holothurians. 



Heretofore the existence of Annelids at the time of deposition of 

 very ancient sediments has been inferred from the presence of certain 

 more or less obscure burrows and trails, but here in the Burgess shale 

 Walcott has been able to recognize eleven genera of these organisms, so 

 perfectly preserved that not only the segmentation of the body but the 

 most delicate appendages can be recognized. The genera are of course 

 all new, and they belong to widely separated families, indicating a 

 remarkable degree of differentiation at this very early period. 



Descriptions of the numerous Phyllopod crustaceans which are said 

 to be associated with the organisms discussed in the three papers here 

 noticed, have not yet been published. They will doubtless be made 

 the subject of another paper in this same volume of Cambrian Geology 

 and Paleontology. S. W. 



Seismic History, of the Southern Andes (Historia sismica de los 

 Andes M eridionales . Por el Conde Fernando de Montes- 

 sus de Ballore, director del Servicio Sismolojico de Chile. 

 Primera Parte. Santiago de Chile, 191 1). 

 As is well known, one of the most unstable regions upon the globe is 

 represented by the great Cordilleran backbone of South America. Yet 

 until quite recently little has been undertaken on scientific lines within 

 that vast region, and its seismic history has been a closed book. When, 

 as a consequence of the object-lesson furnished by the late Valparaiso 

 earthquake, the Republic of Chile established a modern seismological 

 service, it very wisely decided to call to its directorship one of the fore- 

 most of living authorities upon earthquake phenomena. Already famil- 

 iar with the Spanish language from years of residence in Central America, 

 and an experienced compiler of seismic maps and catalogues, it was 

 inevitable that the Count de Montessus would not long delay in exploit- 

 ing the rich mine of seismic facts so long buried in local historical docu- 

 ments. This agreeable task the new director has undertaken, and the 

 wealth of the material has proved even greater than was supposed, so 

 that it will fill several volumes. The first of these has just appeared and 

 is entitled "Seismic History of the Southern Andes" {Historia sismica 

 de los Andes M eridionales. Por el Conde Fernando de Montessus de 

 Ballore, director del Servicio Sismolojico de Chile. Primera Parte. 

 Santiago de Chile, 191 1). 



