2 
assorted according to lengths and placed in separate compartments of 
the aquarium, it was noted that three of the accidentally beheaded 
larvae showed no signs of disintegration. These were placed in 
separate compartments of the aquarium. Two of them lived for several 
weeks and a third for upwards of three months. It was noted that 
in these larvae the head had been severed just in front of the 
anterior gills. 
In the following summer a large number of larvae were decapi- 
tated both by cutting with spring scissors and by pinching with fine 
forceps. The heads were cut off at different levels with a view of 
removing all the medulla. Experience taught, however, that it was 
necessary to leave the external gills. The line of excision which 
resulted in the fewest fatalities was just in front of the anterior gills 
and slightly behind the beginning cerebellum. Although the percen- 
tage of fatalities was very high, many of the larvae survived and 
lived until the yolk was absorbed, usually about three months. In 
1903-’04—’05 large numbers were again decapitated, almost exclu- 
sively by pinching. The percentage of fatalities was much lower so 
that a fairly complete embryological series was obtained. The present 
notes are confined to those features which are obvious from surface 
study. 
Growth. 
Larvae 15-16mm. The normal larvae selected for the experi- 
ments, on July 6th, were still within the surrounding envelopes 
although they were about ready to hatch. By gently rupturing the 
envelopes the larvae are set free when they straighten out to a length 
of 15-16 mm. The general form of the body as seen in profile is 
represented in Fig. 1. At this time the eye is well defined; the 
mouth is formed although the enlarged extremities of the mandibular 
arches have not coalesced to complete the lower jaw; the three pairs 
of gills are well defined, the anterior being about twice the length 
of the posterior. The anterior limb-buds stand out prominently while 
the posterior are discernible. The yolk has changed in contour from 
a spherical to an irregular oval. Its surface is deeply furrowed with 
small blood vessels which unite to form the large abdominal vein, 
which vein carries the blood to the heart. 
Twenty-five larvae in the above stage were decapitated along the 
line shown in Fig. 1. In all the experiments an effort was made to 
sever the head just in front of the anterior gills. Twenty-four hours 
