462 
ADAM SEDGWICK. 
having apparently disappeared). The prseoral lobes have also 
become markedly bilobed as compared with the previous stage 
(fig- 26). 
Stage E (figs. 30 — 34). — In the next stage (fig. 31), which is 
found early in October in England, the spiral straightens out, 
and the embryo becomes bent double, the ventral surface of the 
hind part of the body being applied to the ventral surface of 
the front portion, and the tail end of the embryo being curled 
round the front end of the head. The bend occurs at the level 
of the eighth somite. 
An embryo straightened out and drawn from the side is 
shown in fig. 30. 
The main features of this stage, in addition to the loss of 
the spiral form, are — (1) the increase in the number and size 
of the somites and appendages ; (2) the closure of the eye-pits ; 
(3) the growth of the lips ; (4) the appearance of a groove in 
the thickened ectoderm on the ventral surface of the prseoral 
lobes ; (5) the presence of a well-marked dorsal projection at 
the level of the anterior bend of the body ; (6) the beginning 
of the ectodermal invagination which will form the stomo- 
daeum; (7) the appearance of a pit at the apex of the oral 
papilla (fig. 33, or. p.) ; and (8) of a perforation on the hinder 
part of the ventral swellings at the base of the oral papillae 
(fig. 33, o. s.). 
"With regard to these points, I may make the following 
observations : 
1. The antennae have become ringed, and the number of 
somites is almost completed. There are ultimately twenty-one 
somites; in this specimen twenty could be made out (fig. 32). 
2. In the specimen figured (fig. 30) the eye-pits were not 
closed ; they remained open in this specimen abnormally late. 
3. The lip-fold has grown considerably, and extended on to 
the ventral surface behind the jaws (figs. 30, 33, L.). 
4. These grooves are shown in fig. 35 (c. g.), which is taken 
from a young specimen of the next stage. They are at first 
wide and shallow, but, as we shall see, soon become deep and 
narrow, and eventually closed. 
