
- $4.00 per Year. 



THE 
~ AMERICAN 








2 
A MONTHLY JOURNAL 
DEVOTED TO THE NATURAL SCIENCES 
IN THEIR WIDEST SENSE. 
Vol. XXIV. JUNE, 1890. No. 282 
2 

4 PAGE 
‘Tue CONCRESCENCE THEORY OF THE VERTE- 
BRATE EMBRYO nee 
arles-Sedgwick Minot, 
muk PERSISTENCE OF AND AL LIFE 
PLANT ANIM 
Soie CHANGING CONDITIONS OF ENVIRON- 
Fe 



CONTENTS. i 
Sor} 
rri 37 fel, 3 leira 
“Tha 
at Martha’ s Vineyard Tae A Age of the tame Prof. 
Marsh on lopus and other Dinosaurs—Extinct 
Quadru 








Mineralogy and Petrography.—Mine ests ogi ical 
News—New Minerals, 
Ce ok gies Siler Woe eee ec E ae i eS cee T i 




Botany.—Some Reasons for Varieties Not Soon 
= orge Baur, 530 ma Out—The Causes of Cypress Knees,. . . . 577 
ee OF AMERICAN ZOOLOGY, J. s Kingsley, 537 | oology.—Phymo: sais of the Aen 
SDITORS’ TABLE | Eea Te 0: of Bojanns in the Unio- 
The Proposed Nations! University at Washington— | nidæ— The Dorsal ae: of Nudibranchs—Zoologi- 
. Next Meeting of the International Geological | cal News: General—Worms—Arthropoda—Celom 
a ae es Concerning Zoological s rapa | and ER in a es—Mam- 
i the Paris Congress of Zoologists tree i 
sang pees _—— to >r Collection of the ee | P -Prak Wrin Gok te Transmission 
logical Society eae ag Ar ee -3 ok sh Epilepsy or ee ae 
Boo LETS, nae ee 
eae aa zA | Archeology and Ethnology.—Classification of EAR oe 
| rows or Spearh r Knives in the National Mu- 
pee Cotte i in E Miaa: Lévy's Struct- | s New Archseological o hæolopi a 
et Classification des Roches Eruptives; Thomas's kar Archzeological ?— H Animal Remains, . 589 
M a: a Bibliographies, s, -554 | ; T 
| PROCEEDINGS OF SCIENTIFIC SOCIETIES, . . . > . 595 
bse E othe Genesis of the | SCIENTIFIC NEWS... ..- SS ate a - 598 
PHILADELPHIA: 


jja Post-Office as second-class matter. 
“Pernt BROS. PUBLISHERS 
SIATH AND ARCH STREETS 

