Embryology. 657 
EMBRYOLOGY.’ 
RESEARCHES UPON THE DEVELOPMENT OF COMATULA. ?— 
The important and complete observations of Barrois on the develop- 
ment of Comatula were made upon materials found at Toulon and 
Villa-Franca, and kept alive in cribs or boxes anchored in the 
harbor of Villa-Franca. He records a singular periodicity in the 
breeding habits of this animal. They deposit several crops of ova 
during a single season (April), and therefore produce several broods 
of young which become successively attached to the arms of the 
parent animals. The development of Comatula covers a period of 
seven days. On the first day oviposition, segmentation, and the 
formation of the blastula takes place; on the second day the gas- 
trula and blastopore is formed; on the third day the enterocoel, 
intestine, water-vascular ring, etc., is formed. On the fourth the 
development of the visceral mass is completed ; on the fifth day 
there occurs the displacement or rotation of the visceral mass, con- 
stituting a sort of metamorphosis ; on the sixth day the skeleton 
is formed, and on the seventh hatching occurs. 
The following general conclusions are submitted by the author 
at the close of the memoir — Fundamental Homologies. The first 
and one of the most important results which have been established 
by the foregoing studies is the proof of the homology between the 
peduncle of the larva of Comatula and the preoral lobe of other 
Echinoderms, between the calyx of the larve of Comatula and 
the body, properly so-called, of the larve of other Echinoderms. 
But, aside from this important homology, the development. of 
Comatula differs in two important respects from that of other 
Echinoderms. i 
First difference. —In the ordinary Echinoderm-larva (Asterias 
body, 
direct] 
“fo the latter is found to be inserted at one edge of the preoral 
uncle), it assumes a terminal position. Nevertheless, we a 
know that if the regular and normal mode of development presents 
, Edited by Prof. Jno. A. Ryder, Univ. of Penna., Philadelphia. 
? Recherches sur le davdloppement de la Comatule, I (C. podton, 
par Dr. Jules Barrois, Directeur du laboratoire de Villefranche. Recuei 
Bale.” {yas Suisse. IV. No. 4, pp. 545-651, pls. XXV-XXX. Genève- 
