212 Association of Geologists and JYaturalists. [Oct., 



sent to him from Rio, by Dr. J. C. Reinhart, with information 

 that this or an allied species, had been seen by him on board the 

 U. S. ship Constitution, Cochin-China, and subsequently in all the 

 ports of the Pacific — the ship touching at the Sandwich Islands 

 and Western Mexico, and passing Capes Horn and Brazil, — a 

 wider geographical distribution than has heretofore been given to 

 this genus. The insect proves to be an Evania, and its extensive 

 distribution is attributable to the fact, that this genus is parasitic 

 on the Blatta (or cockroach) which is known to be extensively 

 abundant upon ships between the tropics. 



In the afternoon, Mr. J. E. Teschmacher, of this city, made a 

 communication upon the subject of the fossil vegetation of an- 

 thracite coal, showing that the plants of which the coal is formed, 

 are the same as those found in the shale. He treated his subject 

 under the five divisions of the external parts of plants — the inter- 

 nal parts, the vessels, the leaves, and the seed. Several speci- 

 mens of coal were exhibited by Mr. T. to illustrate his ideas upon 

 the subject. They were very beautifully marked by leaves, seeds 

 and vessels of plants. 



Professor Agassiz made a communication upon the subject of 

 echinoderms, showing that there is no essential ditference between 

 the types of families of echimus and asterias. He explained 

 many points in the animal economy of the echinoderms not be- 

 fore known, and showed the affinities existing between the echi- 

 nus and asterias. He fully proved great uniformity of structure 

 in the two genera. He showed that asterias has an external skel- 

 eton as well as echinus. He explained the circulation, and while 

 speaking of the functions of certain organs, took occasion to ob- 

 serve that physiologists were greatly in error when they deter- 

 mined an organ by its function. He also showed the existence 

 of minute aquatic tubes or canals, and of gills in both genera. 

 The echinoderms when first taken from the water, are of a bril- 

 liant red color, but they shortly change to a bright green after death. 

 They can only be obtained from water to the depth of from 90 to 

 150 and 200 feet. Professor Agassiz had a month's excursion in 

 one of the United States surveying vessels. Lieutenant Commanel- 

 ing Davis, on the coast, and collected his specimens during this 

 excursion. 



Dr. Le Coute, of New York,'made a communication upon speci- 

 mens of five new species of fossil mammalia, discovered at Galena, 

 111. He believes them to belong to the Tapiroids and Suclline 

 families. 



Professor Hitchcock read a letter from Robert Chambers, of 

 Edinburgh, asking for information of the terraces or former sea- 

 levels of this country. Professor H. said it was an interesting 

 subject, and he hoped that information might be elicited from 



