INTEENAL ANATOMY. 207 



ternite." On the contrary, tlie abdomen seems to me 

 to consist of ten segments, the dorsal arches of which 

 are regularly formed. I agree also with Dr. Dickie that 

 the ovipositor is formed by elements which belong 

 partially to the eighth and partially to the ninth seg- 

 ment. The posterior margin of the ninth ventral ab- 

 dominal plate is deeply bifid (PL LXVI, fig. 5), and 

 forms four triangular projections, of which the two 

 central project nearly twice as far as the lateral. 



According to Nicolet's figure,^ Nicoletia has a well- 

 developed ovipositor. 



In lajjijx the eighth and ninth abdominal segments 

 are altogether deprived of ventral appendages, and this 

 is also the case in Gampodea. The sexual orifice is 

 situated, as in the other genera, behind the eighth 

 ventral shield in a conical protuberance, which is 

 simple in the male, but in the female almost bifid. 



The posterior abdominal segment bears three ap- 

 pendages in Lepisma, Lepismina, Machilis, and Nicoletia, 

 but only two in Gampodea. In Lepisma they are nearly 

 equal in size ; in Lepismina and Nicoletia the central is 

 longer than the two lateral, and this difference is still 

 more marked in Machilis. In Lepismina the appen- 

 dages are short ; in Lepisma, Machilis, Nicoletia, and 

 Gampodea, they are long and multiarticulate. Lastly, 

 in lapijx they are modified into a pair of horny forceps, 

 which give the animal very much the appearance of a 

 Forfic'ula. 



Liternal Anatomy. 



The respiration is tracheal. Treviranus was himself at 

 first of this opinion, but subsequently abandoned it, and 

 came to the conclusion that Lepisma breathes through 

 the general surface of the skin. He even asks whether 

 the scales are not perhaps respiratory organs ! Latreille 



1 ' Ann. Soc. Ent. France,' 1847, pi. v, fig. 10. 



