March 21, 1902.] 



SCIENCE. 



469 



while still other kinds will set fruits although 

 pollenated while quite immature. 



Lj'Ster H. Dewey discussed 'The Identity 

 of Prickly Lettuce,' stating that a plant bear- 

 ing this common name, and generally con- 

 sidered to be Lactuca scariola, was introduced 

 into the United States in the early sixties and 

 spread with such rapidity as to become the 

 most widely distributed exotic weed. During 

 the summer of 1901 specimens of true L. scari- 

 ola with runcinate leaves were received from 

 Hamilton Co., Ohio, and this led to a reex- 

 amination of the species. It was at first 

 thought that a common form of the American 

 plant having leaves merely spinulose-margined, 

 but entire or slightly wavy in outline, was 

 L. virosa L. This European species however 

 has rather large, oblong-obovate, thin leaves, 

 not twisted to a vertical plane as are the 

 rather thick, firm leaves of our prickly lettuce 

 and further study proved our form to be L. 

 scariola integraia Gren. et Gord. A few 

 specimens examined exhibit a gradation 

 between this variety and the tsT^ical 

 form. 



F. A. Lucas described 'The Armor of Steg- 

 osaurus/ saying that this consisted of large 

 plates standing on edge on the back and 

 several large spines on the tail. The first 

 Stegosaur, Omosaurus, was found in England, 

 and Professor Owen considered that the tail 

 spine belonged on the wrist. The broad dorsal 

 plates found with the first American specimen, 

 belonging to the genus Stegosaurus, were 

 thought to have been imbedded in the skin 

 like the much smaller plates of the turtle 

 Sphargis. It was soon recognized however 

 that they belonged on the back and the animal 

 was restored with a line of plates down the 

 center of the back. Subsequent study showed 

 clearly that there were two rows of plates, one 

 on either side of the median line, and probably 

 but two pairs of spines on the tail. The most 

 recent comparisons seemed to indicate that 

 the large upright plates were not disposed in 

 pairs, but had an alternating arrange- 

 ment, although this was unlike the arma- 

 ture or adornment of any other knovm ani- 

 mal. 



F. A. Luo.is. 



NEW YORK ACADEMY OF SCIENCES. 

 SECTION ' OF GEOLOGY. 



The regular meeting of the Section was 

 held on January 20, with a comparatively 

 large number of members present, and the 

 following program was presented: 



Professor E. P. Whitfield read two papers. 

 The first was upon the Ammonite Heteroceras 

 simplicostatum, in which he emended and 

 elaborated the description of that species 

 which he had given in the Newton and Jenny 

 Report on the Black Hills, published in 1880, 

 the new observations being based upon ma- 

 terial gathered by Dr. E. O. Hovey on an ex- 

 pedition of the American Museum last sum- 

 mer. This material shows conclusively that 

 the three genera Hamites, Ancyloceras and 

 Heteroceras have no independent existence, 

 because single individuals show the distin- 

 guishing characters of all three genera com- 

 bined.. This fact had been suspected by the 

 author when at work upon the Newton mate- 

 rial twenty-five years ago, and it has been 

 hinted at in the writings of Hyatt and others, 

 but these were the first specimens described 

 which settled the question. 



Professor Whitfield's second paper de- 

 scribed a new teredo-like shell from the Lara- 

 mie group of eastern Wyoming, collected by 

 Mr. Barnum Brown, of the American Mu- 

 seum. This teredo, to which the author has 

 given the name Xylophomya laramiensis, is 

 more than an inch in diameter, thus ranking 

 with the largest species of the family known. 



These two papers may be found in full in 

 the current volume of the Bulletin of the 

 American Museum of Natural History. 



The third paper of the evening was by Pro- 

 fessor James Douglas and gave a description, 

 illustrated by a topographic map and numerous 

 lantern slides, of the famous Eiq Tinto group 

 of the copper mines of the Huelva district in 

 Spain. These mines have been worked from 

 time immemorial, the earliest knowledge of 

 them dating from the Phrenicians, who occu- 

 pied the country in the eleventh century, B.C. 

 The Romans also obtained a large amount 

 of copper from these deposits, and it is an in- 

 teresting fact that the slags which they left 

 are purer — that is, freer from copper, than 



