Maech 23, 1906.] 



SCIENCE. 



467 



America. The common species, T. dactyloides 

 (L.) Willd., is found from southern New Eng- 

 land along the coast to Mexico, and in the 

 interior as far north as Iowa and Nebraska. 

 A subspecies occurs in Mexico {T. dactyloides 

 hispidum Hitchcock). Two other species 

 occur in the United States, T. floridanum, con- 

 fined to the vicinity of Miami, Florida, and 

 T. lemmeni confined to southern Arizona and 

 northern Mexico. Four additional species in- 

 habit Mexico and Central America, T. fascicu- 

 latum, T. lanceolatum, T. pilosum and a new 

 species, T. latifolium. In order to show the 

 relationship of this new species to the others 

 of this genus the whole group was worked over. 

 The paper consisted of a key to species fol- 

 lowed by descriptions, citation of specimens 

 and critical notes. The genus was divided 

 into two sections. The staniinate spikelets are 

 in pairs at each .I'oint of the spike. In sec- 

 tion I. these spikelets are both sessile (T. 

 dactyloides and its allies). In section II. one 

 of the spikelets of each pair is pedicelled (T. 

 fasciculatum and its allies). 



M. C. Marsh, 

 Recording Secretary. 



THE NEW YORK ACADEMY OF SCIENCES. SECTION 

 OF GEOLOGY AND MINERALOGY. 



Meeting of January 8, 1906. — Vice-Presi- 

 dent Hovey in the chair. The following 

 papers were read: 



Oeological Notes on the Western Sierra 

 Madre of Chihuahua, Mexico: Dr. Edmund 

 Otis Hovey. 



The paper gave a concise resume with the 

 aid of lantern slides, of observations made by 

 the author upon an expedition made for the 

 American Museum of Natural History in 

 February, March and April, 1905. The route 

 lay southwestward and southward from Ciu- 

 dad Juarez to Ocampo, thence to the railroad 

 again at Minaca. The development of bolson 

 deserts in arid regions and the similar bolson 

 basins in the less arid regions was described. 

 These bolsons have normally no external drain- 

 age, but in many cases they have been invaded 

 by streams from without. The Aros River has 

 cut through several such enclosed basins, as 



is shown by the remains of local conglom- 

 erates and sandstones. The section exposed 

 in the deep canyon of the Aros shows that a 

 foundation of Cretaceous ( ?) limestone has 

 been covered by old andesitic eruptives; that 

 continental movements have raised, tilted, 

 faulted and metamorphosed the limestone, 

 producing schists from clayey beds; that 

 granite has been intruded under and into the 

 limestone; that later and more acid lavas 

 and tuffs (dacites and rhyolites) have been 

 poured out or deposited over the region; that 

 the latest outflows were of basaltic lavas ; that 

 the local conglomerates and sandstones have 

 been formed in constructional basins by the 

 disintegration of the mountain slopes. Many 

 other points of geologic interest were brought 

 out in the photographs. 



Discovery of the Schoharie Fauna in Mich- 

 igan: A. W. Grabau. 



Recent examination of the limestones of 

 the Mackinaw region for the Michigan Geo- 

 logic Survey showed the existence of the 

 Schoharie fauna in the basal portion of the 

 Dundee formation, in a number of localities 

 in the northern part of lower Michigan; 

 notably at Mill Creek, near Mackinaw City, 

 and on Mackinaw Island. Such typical spe- 

 cies as Trochoceras clio, Atrypa, impressa, 

 Rhipidomella alsa, Conocardewn cuneus, 

 Phacops cristatus, etc., characterize this 

 fauna. The strata containing it rest directly 

 upon beds with Leperditia cf. scalaris, and, 

 therefore, of lower Manlius (Greenfield lime- 

 stone or Cobleskill) age, from which they are 

 separated by a pronounced disconformity. 

 The finding of this fauna fixes the date of the 

 great mid-Devonic transgression. 



Preliminary Note on Sporadic Occurrence of 

 Diamonds in North America: George F. 



KUNZ. 



Dr. Kunz pointed out the general features 

 of the occurrence of diamonds in North 

 America, reserving the more complete discus- 

 sion for the next meeting. 



A. W. Grabau, 



Secretary. 

 Columbia Univebsity. 



