
464 THE AMERICAN NATURALIST. [VoL. XXXVI. 
nearly transparent and revealed eight internal mesenterial 
divisions.! 
During the first day the Siderastrzea larvae remained near 
the surface of the water or gathered around the sides of the 
vessels in which the colonies were kept. Afterwards they 
traversed the water as a whole, though some preferred the 
neighborhood of the bottom of the vessel From the first 
day many would sink to the bottom and there lie motionless 
for a time, after which the swimming movements might 
recommence. 
By the evening of the second day a few individuals had 
fixed themselves permanently, either to the sides or bottom of 
the vessels, or to the foreign objects partly incrusted by the 
parent colonies. At first the larvae would 
adhere by means of the actual tip of the 
narrow extremity, but this would soon 
flatten out and form a broad base, a small 
rounded oral aperture appearing at the 
free extremity. Whether or not any 
individual larva would settle seemed very 
uncertain, for out of several hundreds set 
free comparatively few became permanently fixed. If fixation 
were not accomplished within the first few days it seemed to 
be impossible afterwards. In one instance about a score of larvae 
were isolated, and nearly all kept alive for a period of twenty 
days, without any of the specimens settling, although various 
suitable objects were placed in the vessels. 
iile many larva fixed themselves isolated from others, a 
decided disposition to settle simultaneously in small groups 
was evident. Thus in Fig. 1, where three larvae are repre- 
sented, all in the first stage of fixation, their narrow apices are 
so close as to be nearly touching. It is clear that when they 

1 The larve of West Indian corals are usually set free at a stage at which 
three or more pairs of mesenteries are already developed, the stomodzeum fully 
formed but non-functional, and the interior wholly, or in part, occupied by a 
lated tissue breaks. dein and i is seen to be extruded at intervals through the oral 
aperture. 
