MAYER: STAUROCEPHALUS GREGARICUS. e 
Kleinenberg’s hematoxylin, and appear to be filled with a mass of 
deeply stained granules that may represent the coagulum of some fluid. 
Figures of these cells, in older larve, are shown in(g/) Figures 7, 8, 
Plate 1. I believe them to be glands, and they are probably homologous 
with the “frontal bodies” found by Wilson (’92, p. 421) in the larva of 
Nereis, and perhaps also with the “problematic bodies” observed by 
Mead (97, p. 256) in the larva of Amphitrite. Malaquin (93, p. 395, 
Plate XIV., Figures 12-16) has also found glands in a similar position 
in the head of the larva of Autolytus Edwarsi. 
Figure 15, Plate 2, represents a larva 3} days old, and Figure 7, 
Plate 1, shows a dorso-ventral section of the same. The eyes are now 
quite large, and the green patch representing the gland cells is very 
prominent. There are now three bands of cilia: a broad oral band, 
a narrow post-oral, and an anal band. Two sets of sete, consisting 
each of three bristles, have made their appearance immediately posterior 
to the post-oral band of cilia. These sete originate in folds of the 
hypodermis. A longitudinal dorso-ventral section (Figure 7) of the 
worm in this stage shows the very large gland cells (g/) of the head. 
The mouth (m) shows signs of being about to break through, although 
as yet it is not functional. The same may perhaps be said of the anus 
(an). The mid gut (sé) of the worm now consists of a delicate ento- 
dermal epithelium enclosing a mass of highly vacuolated cells laden with 
yolk spheres. 
Figure 16, Plate 2, shows a larva 5} days old, and Figure 17 illus- 
trates the character of the sete from the same worm. Most dorsal 
of all there is a single long seta (Figure 17, 4) and immediately be- 
low this there are two sete of the sort shown in Figure 17, a. 
Figure 18, Plate 3, shows a larva’ 10 days old. The worm is now 
0.5 mm. in length, and possesses three sets of sete. Until the end of 
the 15th day the larve are remarkable for exhibiting a strongly posi- 
tive phototaxis. They swim through the water at all depths, but 
large numbers of them are sure to be found clustered together in 
those parts of the aquaria where the light is strongest. 
At the end of the 15th day the cilia disappear, and the worms cease 
to swim through the water, and sink to the bottom. Figures 19, 20, 
represent a young worm that is 16 days old, and Figure 8, Plate 1, 
shows a dorso-ventral longitudinal section of the same. There are 
now four pairs of parapodia provided with dorsal and ventral cirri. 
A number of sensory hairs are found scattered over the preestomium, 
and the posterior segment of the body exhibits a pair of dorsal cirri. 
