187 
more rapid. One or two eyes of orange-red colour were 
also present on the anterior portion of the larva. During 
the third day the animal elongated and contracted at in- 
tervals, and evidently both longitudinal and circular 
muscle fibres were present. At the end of the third day 
the telotroch* larva worked its way out of the vitelline 
membrane through a thin area which had previously made 
its appearance (fig. 75). 
When hatched the larva was about ‘25 mm. long. It 
either crawled on the bottom of the dish or swam actively 
by means of its cilia. Between the two bands of cilia 
there appeared on the ventral surface a broad longitudinal 
band of short cilia. Soon after hatching a small spade- 
shaped seta (7u long) was observed in one specimen. It 
could be protruded and retracted (fig. 76). The larvee 
grew very slowly in the laboratory and it was not until 
more than four days after hatching that the setz of the 
following segment appeared. In the meantime the 
spatulate sete of the first segment had been reinforced by 
the addition of a seta with a long, drawn-out tip, and a 
little ventral to this the first crotchet appeared. Two days 
later the alimentary canal seemed to be complete from 
mouth to anus, its central part was rather distended with 
yolk. The celom was quite obvious post-orally, and the 
ventral body wall was thickened, due to the formation 
there of the ventral nerve tract. The two belts of cilia 
and the longitudinal ventral band gradually decreased in 
size from this point onwards. Two days later another 
segment acquired its sete. Both the chetigerous seg- 
ments in front of this had on each side two sete and a 
crotchet, the third segment bore only the newly formed 
spatulate seta. The larve crawled about the bottom of 
** The term applied to Polychete larve in which the cilia are 
arranged in two bands forming a preoral and a peri-anal ring. 
