No. 2.] DEVELOPMENT OF MANICINA AREOLATA. 193 
which includes the skeleton below this region, is usually disfig- 
ured by small annelid tubes and other incrustations. 
The young, after the swarming life is over, affix themselves 
to some solid substratum, such as a piece of rock or a shell. 
To this they remain attached until they have reached a diameter 
of about half an inch. Until the diameter is one-third of an 
inch, the animal remains a single polyp, circular or oval in trans- 
verse section, and with a flat or irregular surface of attachment. 
The multiplication by fission then begins, and with it the forma- 
tion of the pedicel. When the latter has become apparent, the 
coral is broken off from the rock to which it was attached, and 
henceforth lives free in the sand. 
II. GENERAL SKETCH OF THE DEVELOPMENT FROM SURFACE 
VIEWS. 
Lacaze Duthier’s figures of Astroides (1) apply so well to 
Manicina, that I have thought it unnecessary to give a series of 
such views. The chief point of difference is that the larve are 
red in the former genus, but colorless in the latter. 
Manicina is hermaphrodite. Normally, it would appear, the 
mother gives birth to larvae, which pass out by the mouth. But 
the first two batches of corals I kept poured out an abundance 
of eggs and semen. Each batch numbered eight corals, was 
distributed into four aquaria, and was kept for only a day. The 
first set laid on the night of the 15th, the second, on the 
17th of March. I was not able to try a third batch until the 
20th, when I was surprised to find that all the corals had given 
birth to larvee a little more advanced than the planula stage. 
The throwing out of eggs and spermatozoa was probably abnor- 
mal, as the eggs which I watched underwent very irregular 
changes, and finally broke up. In connection with this ejection 
of eggs and semen, it may be interesting to note that though 
after March 20 the corals always ejected larvee when kept in 
aquaria, the stage of development in which the larve were 
born became much more advanced as the season grew older. 
The larvz born March 20 and 21 were without cilia, and at the 
stage represented in Fig. 4, Pl. II. Those born April 5 were 
ciliated and as far advanced as Fig. 20, Pl. IV. 
The larve I obtained during March lay, for a day or two after 
