1913] Anatomy of the Squash Bug. 435 



fused together, except dorsally where the chitin is almost mem- 

 branous just anterior to the rectal cauda (re). Its shape is 

 also greatly modified. The dorsal aspect presents a large pit 

 or cavity, above which lies the rectal cauda and the genitalia. 

 The chitinized tip of the rectal cauda is the much modified ninth 

 segment. The rectal cauda projects posteriorly from the dorsal 

 wall of the eighth segment, which is called the pygidium (pg). 

 The basal half of the rectal cauda is membranous above and 

 below, but slightly chitinous laterally. Its posterior half, which 

 lies folded and hidden within the basal portion, is membranous 

 except the tips which are chitinized, and open and close as do the 

 edges of a purse. Beneath the basal portion of the rectal cauda 

 lies the oedeagus, those chitinized portions of the male genital 

 organs through which pass the membranous structures connected 

 with the ejaculatory duct. Posterior to the oedeagus lie two mov- 

 able appendages or styli (la) . The ventral portion of the eighth 

 segment which bears internally the lateral appendages and 

 contains the oedeagus is called the hypopygium (pp). 



Dorsally, the abdomen of the female presents ten segments. 

 The tenth, which forms the chitinous lips of the rectal cauda, 

 is hidden within the ninth, except when extruded, and is widely 

 separated from the ninth by the membranous rectal cauda. 

 The dorsal portion of the ninth segment is called the pygidium. 

 Ventrally, the ten segments are not so easily recognizable, 

 especially when the abdomen is extended, as the segments 

 are variously modified for protective and reproductive purposes. 

 Attached to the insides of the dorsal and ventral portions of the 

 eighth abdominal segment are two pairs of chitinous appendages, 

 the lateral appendages or styli, armed with stiff spines or hairs. 

 These lie above and protect the soft portions of the genitalia 

 when in repose. These appendages may function as claspers 

 in copulation, but actual observation of this function will be 

 necessary to determine this point. The ventral portion of the 

 eighth abdominal segment is called the hypopygium. 



