414 SYNOPTIC COLLECTION. 



anterior part of the body of the cockroach may be seen 

 at first distinctly. In the course of the development a 

 pair of appendages appears on each segment. PL 1005, 

 fig. i, shows one pair of antennae, three pairs of mouth 

 parts, three pairs of thoracic legs, and eleven pairs of 

 abdominal appendages, making in all eighteen pairs. 

 These are alike when first formed and appear before the 

 dorsal portion of the body is completed. Most of the 

 abdominal appendages (which we have already found in 

 the adult Thysanurau insects) quickly disappear, as 

 shown in the older embryonic stages (figs. 2, 3). The 

 body shortens but the distinctness of the segments is 

 preserved. The eyes (fig. 3, c) are plainly seen in this 

 stage. The larvae (No. 1006, Blatta (=. Periplaneta) 

 orientals Linn.) have ancestral and Thysanuran charac- 

 ters, but in addition the adults have certain marked 

 adaptive features. Some of these features are particu- 

 larly well shown in Blatta orientalis Linn. (Nos. 1007, 

 $ ; 1008 9) and in the large Cuban cockroach (No. 

 1009), because in these species the features have been 

 intensified by domestication. The body and leg sections 

 are extremely flattened, and the freely movable segments 

 of the abdomen can be extended or shortened by tele- 

 scopic action, thus enabling the insect to crawl into nar- 

 row crevices. The head is reduced in size and turned 

 under the large prothorax, so that it is scarcely seen in a 

 view from above. The biting mouth parts are hard and 

 dark colored, since the cockroach feeds upon almost any 

 substance that comes in its way. 



Both pairs of wings are well developed in certain 

 genera of this family, Blabera for instance (PI. 1010, fig. 

 i, A, anterior wing ; B, posterior wing), but in Blatta the 

 wirrgs of the male (No. 1007) are diminished in size, 

 while in the female (No. 1008) the forward wings are 

 vestiges and the hinder pair have wholly disappeared. 



Among the more generalized Orthoptera the " praying 

 mantis" (No. ion, egg-case; Nos. 1012, 1013, adults) 



