\ ioMV ,\\l> I'HN 65 



In Kphemerida the two inner \a!v< - are partly or entirely scp. 

 from each other, forming two intromittent Organ Kig. 86). 



In male ( Mnnala, t he eja* ulatory duct opens on the ninth abdonr 

 segment, but the copula tory 'la< ed on the under -ide of the SCC- 



ond segment, to which the spermatozoa arc 1i d by the b' ndin- 



of the abdomen. At copulation, the abdominal Hampers of the male 

 Uia-p the neek of the female, and the latter bends her abdomen for 

 until the tip reaehes the peculiar copulatory apparat n of the male. 



The <7(/.v/>rr.v of the male consist of a single pair, variously fori: 

 They are present in Ephcmerida, Neuroptera, Trichoptera, Lepidoptera 

 (Fig. 87), Dipt era and some Hymenoptera, though not in Coleoptera, 

 and often afford good specific characters, as in Odonata. In butterflies 

 of the genus Thanaos, the claspers are peculiar in being strongly 

 asymmetrical. In Odonata (Fig. 88, ^4) and Orthoptera (Fig. 89, A) 

 the superior appendages of the male often serve as claspers. 



In many insects the tergum of the last abdominal segment forms a 

 small suranal plate (Fig. 89, B, sp) ; this sometimes supplements the 

 claspers of the male in their function, as in Lepidoptera (Fig. 87, A, s). 



2. INTEGUMENT 



Insects excel all other animals in respect to adaptive modifications of 

 the integument. No longer a simple limiting membrane, the integu- 



FIG. 85. Extremity of abdomen of a FIG. 86. Extremity of abdomen of a 



male beetle, Hydrophilus, ventral aspect, g, male May fly, Hexagenia variabilis, ventral 



genitalia; p, penis; t/ 1 , t/ 2 , pairs of valves aspect, c, c, c, cerci and pseudocercus (medi- 



enclosing the penis; 6-9, sterna of abdominal an) ; cl, cl, claspers; i, *, intromittent organs, 

 segments. After KOLBE. 



ment has become hardened into an external skeleton, evaginated to 

 form manifold adaptive structures, such as hairs and scales, and 



