1886.] natural sciences of philadelphia. 231 



April 27. 

 The President, Dr. Jos. Leidy, in the chair. 



On Anthracomai^tus Trilobitus Scud. Prof. F. L. Harvey re- 

 marked that the coal field of North Arkansas belongs to the 

 western interior coal area, which covers the greater part of Mis- 

 souri, and extends into Iowa, Kansas, Nebraska, Indian Territory, 

 Arkansas and Texas. This vast field covers 78,000 square miles, 

 of which about 10,000 are in Arkansas and 12,000 in the Indian 

 Territory. It belongs to the lowest, the suhconglomerate. The 

 veins occur in the shales of the millstone grit, less than 100 feet 

 above the Archimedes limestone. There is only one vein in the 

 northern limit, which is from eight to eighteen inches .thick. In 

 the Arkansas River valley there are three veins which often have 

 an aggregate thickness of over six feet. The veins lie high in the 

 hills in the Boston Mountains, but the southward dip brings them 

 in the Arkansas River valley, beneath the drainage of the country. 

 The veins in north Arkansas are worked in a limited way by 

 scalping and drifting, but shaft mining is done at Coal Hill, 

 Spadra and other points and there is at present considerable 

 coal exported to New Orleans down the Arkansas valley route. 



The conditions were most favorable for the preservation of plant 

 remains. Beautifully preserved plants occur in the shales above 

 the coal vein of northwest Arkansas and limited research in 

 Washington County alone yielded the speaker over 100 species 

 new to the State and fifteen new to science. 



While searching for fossil plants in the brash shale near the 

 coal, a specimen of fossil spider was found. By carefully work- 

 ing over a few tons of shale several more specimens were procured. 

 The material was sent to Prof. Scudder for examination and he 

 named the form Anthracomartus trilobitus, sp. nov. It is believed 

 to be the only species of the genus found in the coal measures of 

 the United States. The genus was founded upon a single Euro- 

 pean species. It is interesting that a second species should be 

 found so far separated. Fossil insects are scarce in the suhcon- 

 glomerate, and the three known from Arkansas are, a wing of 

 Blattina venusta, discovered by Prof. Lesquereux and figured in 

 Owen's Report of Arkansas, vol. ii, p. 312 ; the species of spider 

 under consideration and an undescribed Neuropterous larva in 

 the cabinet of the speaker. The description and figure of this 

 Anthracomartus, so far as we know, has not been published, 

 but is enumerated in Mr. R. D. Lacoe's " Check List of 

 Palaeozoic Insects." Less than a dozen specimens are known and 

 they are in the cabinets of Prof. Scudder, Mr. R. D. Lacoe and 

 the speaker, besides the specimen presented to the Academy 



