1916] Thoracic and Cervical Sclerites of Insects 65 



latter is in the process of disappearing in Dolerus and is rep- 

 resented by a small sclerite on either side of the sternum (Fig. 

 12, pc). These small sclerites are not connected with either 

 the sternum or episternum, but lie half way between them. 

 In Macroxyela all trace of the precoxale is lost (Fig. 14) . There 

 is no indication of the connecting bridge between episternum 

 and sternum, but the sternum is larger than in Dolerus or Abia 

 and probably represents the fusion product of a part of the 

 precoxale and sternum (Fig. 14, vs). 



The terminology of the above discussed sclerites is some- 

 what confused. The precoxale was termed "laterale" by 

 Crampton, '09 and "precoxal bridge" or "precoxale" by 

 Crampton, '14. The pleurocoxale was termed "katopleura" 

 by Verhoeff, '03, in the Forficulidas, and in the Blattidae he 

 applies the same term to an entirely different sclerite, showing 

 that his homologies of the thoracic sclerites are evidently 

 incorrect. It was termed "episternal laterale" by Crampton, 

 '09, and " lateropleurite " by Crampton, '14. The sternocoxale 

 was termed "vorplatte, " by Verhoeff, '03, "sternal laterale" 

 by Crampton, '09, and " laterosternite " by Crampton, '14. 



In introducing the terms pleurocoxale and sternocoxale, 

 an effort has been made to improve the terminology of these 

 sclerites. They are more or less closely associated with the 

 precoxale and antecoxale of Crampton, '14, and all are situated 

 near the base of the coxa. Hence the sclerites composing this 

 region have been given a uniform ending, which with the pre- 

 fix, denotes quite accurately the respective positions of these 

 sclerites. The term trochantin is so widely known, accepted 

 and used that it would not be advisable to change it. This, 

 however, does not apply to the other sclerites mentioned 

 above. 



Trochantin. The trochantin is a more or less triangular 

 shaped sclerite situated at the base of the coxa (Fig. 3, tni). 

 It varies in size being quite large in some insects (Periplaneta, 

 Fig. 3, tn2) and small in other forms. (Tipula, Capnia, etc.. 

 Fig. 4, tni). In some forms, such as in the prothorax of 

 Periplaneta, Capnia, etc., the basal portion of the trochantin is 

 fused for a short distance with the episternum (Fig. 3, tnj. In 

 other insects it is partially or completely fused with the epi- 

 sternum and precoxale or else has disappeared. These various 



