108 ORTHOPTEROUS GROUP INSARAE 



found in this genus is noticed only in the male sex and then in but 

 a portion of the species. The caudal section of the proximo-dorsal 

 segment is elevated dorsad into a process which may be moderately 

 low and sub-obliquely or arcuato-truncate cephalad or compara- 

 tively high, slightly recurved cephalad, inflated, bulbous and more 

 or less finely haired. Apparently this structure is a specialized 

 fold of the chitinous integument, as in a few of the species possess- 

 ing it the caudal aspect evidences its origin, but in the more highly 

 modified structure found otily in certain individuals of gracilipes 

 this feature is not so evident. The very peculiar feature regarding 

 this development is that it is not even a specific character in semi- 

 alata, specimens from the northern part of the range of which have 

 a well developed process, while those from the more southern lo- 

 calities have no trace of this structure. In gracilipes specimens 

 from the higher elevations have the extreme bulbous type present, 

 while those from the lower altitudes have the simpler, more usual 

 type of process. Taken altogether this structure is one of the most 

 puzzling features in the external morphology of the genus, the fact 

 that such a marked development should be variable within specific 

 limits being most unusual. The process is present in all of the form 

 of group A, present (insaroides) or absent (phalangium and graUator) 

 in group B, present {brevicauda and Umifera) or absent {carita) in 

 group C and absent in group D {phantasma) and present or absent 

 in the species semialata. Thus the appendage is seen to be present 

 or absent in species which are evidently members of the same 

 phyla. What the function of this structure may be we do not know 

 and can only suggest that it may be the orifice of a scent gland. 



Notes on Tegyninal Structure. — In the male sex the highly special- 

 ized structure of the stridulating field of the tegmina affords excel- 

 lent specific characters, which we have utilized to great advantage 

 in the present paper. Two tendencies are noticed in the develop- 

 ment of this field, one in the formation of an ample area, long and 

 broad, with a but little differentiated margin and a non-produced 

 apex to the stridulating vein (examplified in phantasma, phalangium 

 and grallator) and another in the more or less pronounced abbrevia- 

 tion of the field, which is broadest at the stridulating vein, the apex 

 of which becomes progressively produced into a peg-like process, 

 the extreme type of which is as long as the remaining width of the 

 field (Umifera). This latter tendency appears to us to be the great- 



