REVIEWS AND BOOK NOTICES. 683 
and shown that in the embryos of the Acalephs and Echinoderms 
the outer layer is invaginated and forms the walls of the stomach. 
And it appears to us that if organs, such as the ovary and testicle, 
almost universally recognized as homologous, are developed from 
opposite germ-layers, then the importance of the germ-layer theory 
of Haeckel is diminished by Van Beneden’s remarkable discovery. 
We should say, however, that at the last meeting of the French 
Association for the Advancement of Science, Mr. P. Hallez ques- 
tioned whether the ovary and testis were homologous. Meanwhile 
Giard announced at the same meeting that the male organs of 
Sacculina, a crustacean, are developed from the frontal glands, 
which in turn arise from the ectoderm. $ 
EETA RERA 
MEF. 
ae eee 
= EEE T LOTINA AIER E E AS 
_ Mars or Wneerer’s Expepirion. — We have received six ad- 
vance sheets of a ‘Topographical Atlas” projected to illustrate 
Explorations and Surveys west of the 100th meridian of longi- 
tude, embracing results of the different expeditions under Lt. 
Wheeler, Corps of Engineers, U. S. A., published by the war de- 
partment. The scale of each atlas sheet is one inch to eight 
miles. Sheet 50 covers portions of central and western Utah; 
sheets 58 and 59 embrace parts of eastern and southeastern Ne- 
vada and southwestern Utah; sheet 66 covers portions of south- 
western Utah, northwestern Arizona and southeastern California. 
The work appears to be well done and will be useful to geographers 
and naturalists studying the distribution of plants and animals, 
_ specially the map of the areas of drainage to the Atlantic and 
Pacific oceans and of the interior basins of the United States, 
West of the Mississippi river. 
We have found exceedingly useful the progress map of lines and 
_ Areas lying west of the 100th meridian, and giving the lines of 
exploration by different parties sent out by government since Lt. 
‘ ’s expedition of 1805; not, however, including the area sur- 
_ Yeyed by parties under the Department of the Interior and Smith- 
Sonian Institution. : 
A large number of sheets are in preparation, and we shall ere 
long with the aid of these and the maps publishing by Hayden and 
Powell’s expedition, with those of Whitney’s Survey of California, 
be in Possession of definite knowledge of the region west of the 
Mississippi, which is now altogether wanting in any atlas we have 
Yet seen. f 
Dy 
i 
