348 WHEELER. (Vor. III. 
have given elsewhere (50) a minute account of the pair of appen- 
dages belonging to the first abdominal segment, I shall not con- 
sider them in the present paper. The pair of appendages belong- 
ing to the terminal segment persist and become the anal stylets. 
Unlike most Arthropod embryos, the caudal end of the embryo 
Blatta (cp!) is never bent dorsally, but from the very early stage 
in which it is in a line with the long axis of the abdomen, shows 
only a ventral flexure. Owing to this flexure, which soon be- 
comes very pronounced, the formation of the protodzeum cannot 
be as easily observed as in Doryphora. 
The changes which are apparent in surface views by the four- 
teenth or fifteenth day have been carefully represented in Figs. 
46 and 47. In the former the embryo is zz sztu on the yolk, in 
the latter it is isolated and seen from the ventral surface. 
As may be indistinctly seen in Fig. 47, the first and second 
maxillary appendages have each become split up into three divis- 
ions. In @canthus, according to Ayers, “the three oral appen- 
dages are trilobed ; the lobation is most prominent in the second 
maxillary, and least in the mandibular appendages. The primi- 
tive appendage is first divided into two lobes, and the inner of 
these becomes secondarily divided into two.” There are appar- 
ently no traces of lobation in the mandibles of Alatta. The 
outer of the three lobes of each maxilla becomes the palp, while 
the inner two become the galea and lacinia of the adult. 
fig. 9. Fig. 70. Fig. 77. Fig. 12. Fig. 73. 
figure 9.—Embryo of Blatia, 15 days old; revolution about to begin. The 
stages in revolution are represented, after the rupture of the amnion and serosa, in 
Figures ro-13, which are from embryos 16, 163, 163, and 17 days old respectively. 
as. amnion and serosa; s. edge of serosa; J. dorsad growing body wall; d. o. dorsal 
organ; «. clear zone covered with scattered amniotic nuclei. 
