280 The American Naturalist. [March 
spongin skeleton of thin, simple or branched spongin fibrillz, not an- 
astomizing nor reticulated, together with the usual symbiotic hydroids. 
Prof. Haeckel believes that these fibrils throw light upon the peculiar 
filaments of the Hircinide. They are monaxial keratose spicules. 
This report occupies ninety-two pages, and is illustrated by eight plates. 
Ccelenterata.—The last volume of the Challenger Zodlogical 
Reports, Vols. XXXI. and XXXII., have lately been issued. The first 
of these contains the important report upon the Alcyonaria, by Messrs. 
Wright and Studer, and the comparatively short account of the pelagic 
fishes, by Dr. A. Gunther. Of the 189 species of Alcyonarians found 
by the expedition, 133 are here described as new. From the chapter 
upon geographical distribution, it appears that the West Indian Isles, 
the western shores of North America, and the Australian and Japanese 
seas, are the headquarters of this group. The report occupies 386- 
pages and is illustrated by 49 plates. 
The first report in Vol. XXXII. is by G. Brook, and treats of the 
little known group of the Antipatharia. As most of the specimens of 
Antipathes preserved in museums are in a dry and shriveled condition, 
good diagnoses of the species are rare. Fortunately most of the Chal- 
lenger examples had the polyps well preserved, and, therefore, a partial 
revision of the tribe has been attempted, and the classification put upon 
a correct natural basis. Nearly all the species are new, and are mostly 
from localities whence no forms were before known. Littoral forms 
are remarkably deficient. Besides the species found by the Chal- 
lenger, other new forms already in the British Museum are described. 
The report contains the first detailed outlines of the structure of the 
group yet given. The structure of the genera is described, and the forms 
of the zooids, as well as the number and proportion of the mesenteries, 
are detailed. Four of the species occurred between 2,000 and 3,000 
fathoms. The Antipatharia approach the Cerianthide more than the 
Hexactiniz in the arrangement of the mesenteries, and in the relatively 
thin mesoglea, devoid of stellate connective tissue cells, the rudimentary 
musculature of the mesenteries, etc. This report has 222 pages, an 
15 plates, 
Echinodermata.—J. Georg (Archiv für Naturgeschichte, Sept., 
1889), gives reasons for the belief that the echini excavate their holes 
in the rocks not by any chemical solvent, but by their teeth, As they 
enter young, the bottom of the hole is larger than the entrance, and 
thus the tenants are prisoners, ‘dependent for food upon such forms of 
life as are brought by the currents, such as foraminifera, etc. Though 


