Association of American Geologists and Naturalists. 135 



geographical distribution than has heretofore been given to this 

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

 bution is attributable to the i'act, that this genus is parasitic on 

 the Blatta (ur cockroach) which is known to be extensively abundant 

 upon ships between teh tropics. 



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

 communication upon the subject of the fossil vegetation of anthra- 

 cite coal, shewing that the plants of wliich 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 internal parts, the 

 vessels, the leaves, and the seed. Several specimens of coal were ex- 

 hibited by Mr T, to illustrate his ideas upon the subject. They 

 were very beautifully marked by leaves, seed, and vessels of plants. 



The Rev. Mr Hincks of London, recently arrived, presented to the 

 Association a specimen of recent vegetation, for their examination. 



Professor Agassiz made a communication upon the subject of 

 Echinoderms, shewing that there is no essential difference between 

 the types or families of Echinus and Asterias. He explained many 

 points in the animal economy of the Echinoderms not before known, 

 and shewed the affinities existing between the Echinus and Asterias. 

 He fully proved great uniformity of structure in the two species. 

 He shewed that Asterias has an external skeleton as well as Echinus. 

 He explained the circulation, and while speaking of the functions of 

 certain organs, took occasion to observe that physiologists were 

 greatly in ei-ror when they determined an organ by its function. 

 He also shewed the existence of minute aquatic tubes or canals, and 

 of gills in both species. The Echinoderms, when first taken from 

 the water, are of a brilliant red colour, 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 ves- 

 sels, Lieutenant Commanding Davis, on the coast, and collected his 

 specimens during this excursion. 



Dr Le Conte, of New York, made a communication upon speci- 

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

 111. llo believes them to belong to the Tapiroids and Suelline 

 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 Hitchcock said it was an interest- 

 ing subject, and ho hoped that information might be elicited from 

 members of the Association. He stated tliat terraces existed on 

 tho banks of the Jordan in Asia, similar in character to the terraces 

 formed in tliis country. Upon the banks of our streams there are 

 usually two terrace levels. Mr Chambers says that the terraces of 

 Groat Jiritain bear tho same level throughout the country. 



Piofessof Hitchcock thought that this could not bo the case in 



