PARACOROTOCA AKER.MANI (aVARREN). 319 



have the appearance of being- formed Ijy the fusion of at 

 leHst three elements, wliich doubtless may be regarded as the 

 pro-, meso- and metatergites of a typical tergite. 



The tergite of abdominal segment VII, although plate- 

 like, also shows some signs of a compound nature; but the 

 tergites of abdominal segments VIII and IX are simple plates. 

 The thin tergite of abdominal segment VIII supports a 

 forwardly directed swelling (PI. XVII, fig. 33, and PI. XVIII, 

 ah. sic), which is largely filled with blood-tissue. This 

 swelling is probably a supplementary exudatory structure. 



The position of abdominal spiracles III-VI at the ends of 

 the tergites on the inside of the longitudinal ridges confirms 

 the view that the inflation of the abdomen results from a 

 ventral expansion, while the dorsal surface remains relatively 

 unaffected. 



A'entral Surface. — The abdominal stalk which joins the 

 thorax consists of abdominal segments I and 11. Each side is 

 covered by a curved chitinous plate continuous with the tergite 

 of abdominal segment II (fig. 2, T.II). The ventral surface of 

 the stalk is not provided with special sternities; it is covered- 

 with a continuous, somewhat thick cuticle carrying long setie 

 (PI. XVIII). In one specimen an obvious transverse groove 

 occurred in the middle of the ventral surface of the stalk, and 

 this would seem to indicate the division between the 1st and 

 2nd abdominal segments ; but such a groove could not be 

 detected iu all the sjDecimens. 



Expansion and up-bending occur in segment III. The 

 ventral and posterior surface of this segment is richly setose. 

 There is no development of a definite sternite in this 

 segment. 



Abdominal segments IV-VIII are provided with relatively 

 large, arched sternites, each consisting of a narrow piece in 

 front (topographical) and a much wider piece behind (PI. XVI, 

 figs. 1 and 9, also text-fig. 3) ; the former is metasternite 

 [rat. N.), and the latter in section is seen to consist of a front 

 poi-tion or mesosternite [ms. s.) and of a hinder portion, 

 presumably composed of pro- and acrosternites (jj. st.). 



