, 



ANATOMY AND PHYSIOLOGY 



Ephemerida the two inner valves are partly or entirely separate 



j from each other, forming two intromittent organs (Fig. 86). 



In male Odonata, the ejaculatory duct opens on the ninth abdominal 

 segment, but the copulatory organ is placed on the under side of the sec- 

 ond segment, to which the spermatozoa are transferred by the bending 

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

 grasp the neck of the female, and the latter bends her abdomen forward 

 until the tip reaches the peculiar copulatory apparatus of the male. 



The claspers of the male consist of a single pair, variously formed. 

 They are present in Ephemerida, Neuroptera, Trichoptera, Lepidoptera 

 (Fig. 87), Diptera 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 t s). 



2. INTEGUMENT 



Insects excel all other animals in respect to adaptive modifications of 

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



i - 



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; v 1 , v 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, i, intromittent organs, 

 segments. After KOLBE. 



ment has become hardened into an external skeleton, e vagina ted to 

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



