303 [Jackson. 



with the adult period of the individual. He also pointed 

 out the departure of the whorl among the aberrant Ammo- 

 noids from its complete development among the normal 

 forms, its final appearance as a straight tube in the Baculite, 

 and the close connection between this morphological degra- 

 dation of the whorl and the production of the degradational 

 features in the declining period of the individual, demonstrat- 

 ing that both consisted in the return of embryonic or proto- 

 typical characteristics of the form, and partly of the structure. 

 He said that the individual was, with regard to the major- 

 ity of its peculiarities, either an embryonic, an adult, or an 

 old age form in proportion to its zoological rank. The earlier 

 and simjjler species were embryonic, like the young individ- 

 ual ; the intermediate, or least embryonic in aspect like the 

 adult or progressive period of the individual ; and the later or 

 old age forms, comparable in many respects with the old age 

 of the individual of the progressive forms : and that this 

 could be accounted for by the constant tendency observed 

 in the young of the higher species, to adopt the adult, and 

 finally the old age peculiarities of species which were lower 

 than themselves ; thus making their whole aspect more pro- 

 gressive, or more degradational, in proportion as the preced- 

 ing, or simpler species were progressive throughout life, or 

 began to show degradational features in their later periods. 



Dr. C. T. Jackson exhibited specimens of the pohshed 

 rocks of Smoky Valley, Nevada, having a brilliant, but 

 striated, surface, looking like a porcelain glaze; a polish 

 supposed to be the joint eflect of snow and sand slides, fin- 

 ished up by the more delicate touch of blowing sand. This 

 must have been effected in prehistoric times, for there is now 

 no loose sand in the valley which could be blown by the wind. 



The scratches and polish were not caused by glacial action, 

 since they run directly down the steep slope of the moun- 

 tain, and glacial grooves would course along their sides. 

 Prof WilUam P. Blake of Oakland, Cal., first suggested that 

 rocks could be highly polished by blowing sand, as appears by 

 his statements in the Reports on the Pacific RailroadSurveys. 



It is well kno^\Ti that blowing sand grinds the glass of the 

 United States lighthouse on Cape Cod, and the delicate 



