Aloi'ST 29, 1902. 



SCIENCE. 



349 



cussed by Messi-s. Webster, Ward, Eigen- 

 iiiann and Hay. ) 



A Remarkable Turtle from the Loup Fork 

 Beds of Kansas: Oliver Perry Hay, 

 American Museum Natural History. 

 (Will appear in full in Bulletin Amer. 

 Mus. Nat. Hist.) 



The turtle in question was one of Cope's 

 species, Testudo orthopygia, which possesses 

 an armor of bony plates in the skin of the 

 legs, tail, etc. (Discussed by Professor 

 Ortmann. ) 



MORNING SESSION, JULY 2. PROFESSOR E. L. 

 MARK IN THE CHAIR. 



'The Harvard Emhryological Collection: 

 Charles Sedgwick Minot, Harvard 

 Medical School. 



The speaker described the methods used 

 in the formation of the Harvard Embryo- 

 logical Collection, the general plan for 

 which was laid before the Association at its 

 Detroit meeting. The collection since then 

 has grown steadily, until it now contains 

 527 series, representing carefully chosen 

 stages of embryos of nineteen typical verte- 

 brates. It has already served as the basis 

 rf a series of investigations, and it is hoped 

 that workers from other institutions will 

 also use the material for their special re- 

 searches. The collection is being added to 

 at present with considerable rapidity. The 

 two types, of which the series at present are 

 most complete, are the dog-fish, Squalus 

 acanthias and the chick. (Discussed by 

 Dr. H. B. Ward.) 



Effects of Altitude on Snails of the Species 



Pyramidula strigosa Gould: Morton 



John Elrod, University of Montana. 



The shells belonging to this species are 



air-breathing and land forms. The species 



is widely distributed west of the Rocky 



Mountains, as yet found in only a few 



places east of the main range. It shows 



very great variation. Formerly many spe- 



cies were recognized, but these have lately 

 been reduced to varieties. The paper is 

 based on specimens collected in western 

 Montana. These were taken at altitudes 

 varying from 2,300 to 9,000 feet. The to- 

 tal number examined was nearly 550. 



The measurements included the greatest 

 width, least width, depth, number of whorls, 

 weight, volume and markings. The results 

 show that the shells have even greater vari- 

 ation than was at first supposed. The ex- 

 tremes in greatest width are 6 and 25 mm. ; 

 in least width, 5 and 22 mm. ; in depth, 3 

 and 17 mm.; in whorls, 3.5 and 6.5; in 

 weight, .1 and 1.2 g. ; in volume, .1 and 1.7 

 c.c. The greatest variation was found at 

 lower altitudes, the high altitude forms 

 showing a more fixed condition, with least 

 tendency to deviate from the typical form. 

 All the lines of variation shown in the tables 

 for lower altitude shells show a tendency to 

 vary from the typical form at a given place. 

 From a study of the specimens secured it 

 seems evident that the species has crossed 

 the range and is now descending on the 

 eastern slope. Specimens collected from 

 the eastern or Atlantic side of the range are 

 quite different in appearance from those on 

 the Pacific side, being noticeably of greater 

 depth, and with characteristic shell appear- 

 ance and markings. 



Structure of the Pelvic Girdle in the Sau- 

 ropoda: John Bell Hatcher, Carnegie 

 Musemn. 



The speaker discussed the various ele- 

 ments of the pelvis of Diplodocus, Bron- 

 tosaurus and Morosaurus, the three most 

 common and characteristic genera of sauro- 

 pod dinosaurs. The distinctive characters 

 shown in the pelvic girdles of these three 

 genera were illustrated and the view main- 

 tained that many supposed generic charac- 

 ters exhibited in the pelvis of the Sauro- 

 poda are in reality due entirely to 

 differences of age, hence are of little value 



