104 ENTOMOLOGICAL SOCIETY 



articulating by its lateral angles (i) with the posterior dorsal 

 angles of the epimera. 



The metapleurum in beetles is of special interest (figs. 20, 

 22, 26, and 2y). An episternum and epimerum are always 

 present and usually a postepimerum (figs. 20 and 22, Pepni) or 

 small plate lying dorsal to the epimerum. In Calosoma scru- 

 tator (figs. 26 and 27) the wing process {WP) is clearly an 

 arm derived from both the episternum and the epimerum and 

 a continuation of the pleural ridge. Only one parapterum (P) 

 is present, and this has the form of a short heavy arm lying 

 in front of the wing process, movably articulated to the upper 

 part of the episternum and bearing a large muscle disc inter- 

 nally. A few others of the lower beetles have a similar parap- 

 terum, but in most of the Coleoptera it is as shown by Cyllene 

 robinicc (figs. 20 and 22, P). Here the parapterum is solidly 

 fused with the anterior part of the episternum and its exposed 

 part looks like an arm of the latter equivalent to the wing 

 process. But a careful study shows that the wing process 

 {WP) still unites elements from both the episternum and 

 epimerum and is continuous with the pleural ridge (PR). 



THE EUPLEXOPTERA. 



The illustrations presented in this order are based on two 

 species : Spongophora apicidentata and S. brunneipennis. The 

 resemblance of the Euplexoptera to the Orthoptera is of course 

 well known, but in the thorax there is a fundamental departure 

 from orthopteran characters and a i.narked similarity, though 

 possibly an accidental one, to coleopteran structure. 



The microthorax (fig. 13) is like that of those Orthoptera 

 having this segment best developed. Its sternal plates are 

 larger even than in Orthoptera. The submentum {Sni), how- 

 ever, is attached to the cranium far in front of the neck scler- 

 ites, a distinctly non-orthopteran character. Though there is no 

 gula as in Coleoptera, yet the anterior sternal plate of the 

 microthorax occupies a distinctly gular position. 



The prothorax (fig. 10) is of special interest because its 

 pleural parts closely resemble those of the mesothorax and are 

 little inferior in size. A distinct katopleure is not present but 

 all the other sclerites are well developed. On the other hand 

 the metapleurum is very different from both the propleurum 

 and the mesopleurum. Hence, we have here a prominent 

 departure from the Orthoptera where the propleurum is invari- 

 ably reduced and the mesopleurum and metapleurum are alike. 

 On the other hand, the coleopteran structure is suggested, 

 where the propleurum and mesopleurum resemble each other 

 more than they do the metapleurum. 



