322 



APPENDIX. 



transported by ice from the north, and spread over the surface 

 down to the parallel of about 40°, and of finer material still farther 

 south along the great valleys, extending in the Mississippi Valley, as 

 Prof. E, W. Hilgard has shown, even to the Gulf of Mexico. The 

 transportation was probably, for the most part, the work of a 

 continental glacier, covering a large part of the continent north of 

 40°, and of the floods proceeding from its final melting. Europe 

 also had, at the same time, its northern glacier, reaching down to 

 the parallel of 50°, along which parallel the temperature is about 

 the same as on the parallel of 40° in North America. 



The Glacial period in North America was an era of greater 

 continental elevation than now exists — at least for the glacial 

 latitudes, that is, from the parallel of 40° northward. It was 

 followed by the Champlain era, the era of a subsidence of the land 

 below its present level, over the same northern regions, which 

 subsidence was accompanied by a moderating of the climate, and 

 a melting of the glacier. Next came the Terrace era, marked by 

 the elevation of the continent toward, and finally to, its existing 

 height, and a consequent making of terraces along river valleys, 

 around lakes, and on many sea borders. 



II. RADIATES. 



Polyps have been described as constituting one of the grand 

 divisions of Radiates. 



Radiates are characterized by a radiate system of structure, 

 apparent both externally and internally : in other words, they 

 consist of different series of similar parts repeated around a 

 vertical axis. In polyps the tentacles are thus repeated ; so, also, 

 the internal septa ; the reproductive system ; the eyes, where these 

 exist ; and so on through the structure. In order to make this 

 distinctive feature of Radiates more intelligible, a few words are 

 here presented on the other grand divisions of the Animal Kingdom, 

 or the Sub-Kingdoms as they are called. The number of Sub- 

 Kingdoms is five, as follows : 



1. Sub-kingdom of Vertebrates. — This designation refers to a 

 fundamental feature of the species, — the backbone or spinal column, 

 consisting of a series of bones (sometimes cartilaginous only), 

 articulated together, called, in the Latin language, vertebrcB. In 

 connection with this, they have a cavity above for the great nervous 

 cord, and one below for the viscera. Here belong Mammals (or 

 Man, Quadrupeds, Whales, and the like), Birds, Reptiles, Fishes. 

 All other animals are i)ivertebralcs, that is, have no vertebral 

 column. 



2. Sub-kingdom of AUTICULATES — so named with reference to 

 the fact that the body consists of a series of segments or joints, 

 articulated together ; and that all the legs, antennae, and other 

 appendages, are likewise jointed (articulated). The body has one 



