160 The American Naturalist. [February, 
dates, so far as they have appeared. January, March rst; Feb- 
ruary, May 31st; March, June 28th; April, August 15th; May, 
September 28th; June, December 1st; July, November 18th; 
August, January 5th, 1890; September, February 4th, 1890. 
The numbers for the present year, it is anticipated, will be issued 
on time. 

RECENT LITERATURE. 
“ Challenger” Voyage.—W. P. Sladen’s Asteroidea.'— 
The thirtieth volume of the Challenger Reports is a double one, con- 
sisting of 935 pages of text, and of 118 plates anda map. The re- 
port does not confine itself to the star fishes collected by the Challenger, 
but includes also those taken by the Lightning, Porcupine, Knight- 
Errant, and Triton. In the Challenger collection were 268 species be- 
longing to 84 genera, and of these 184 forms are described as new. The 
total number of new species described in the work is 196, besides 15 
forms that are considered as only varieties. Mr. Sladen reduces 
Perrier’s 52 genera to 49, three of the genera proving invalid or syn- 
onymous, and the Challenger Expedition furnished examples of 38 of 
these previously known genera. So large a number of new genera 
have been described that the synoptic list of all known species of recent 
Asteroidea, given at the end of the Report, enumerates 137 genera and 
810 species. 
The long list of of abyssal Asteroids brought to light by the Chal- 
lenger and other deep sea expeditions, has opened a new chapter in 
the history of the Asteroidea, and Mr. Sladen has attempted a classi- 
fication upon a new basis, more in accordance with morphological 
characters than preceding ones. The fundamental points of structure 
selected by Mr. Sladen are: (1) those which adapt the organism for 
the functions of respiration and excretion; (2) the character of the 
ambulacral skeleton ; and (3) that of the ambital skeleton. 
For the first he chooses the organs called ‘‘ papulz’’ by Stimpson, 
transparent membranous czca which penetrate the body wall, and 
permit an exchange by osmosis with the free fluid without. These 
papulæ may be confined to a limited area on the abactinal surface, 
never passing beyond the boundary of the supero-marginal plates (Ste- 
1 Voyage of H. M.S, Challenger. Report on the Asteroidea collected during sos 
By W. Percy Sladen, F.L.S., F.G.S. Vol. XXX. 1889. 


