1918.] NATURAL SCIENCES OF PHILADELPHIA. 171 



The male genitalic characters can be briefly described as follows. 

 The disto-dorsal abdominal segment has the distal margin concave 

 mesad, the concavity delimited laterad by a short black projecting 

 tooth; supra-anal plate of the trefoil type found in this genera 

 group, the paired lateral sections strongly rounded, the median 

 distal section short sublinguiform, the dividing emarginations 

 roundly rectangulate, proximal half of plate with a median sulcus, 

 widening distad; cerci developed as broad plates but slightly sur- 

 passing the apex of the supra-anal plate, the dorsal section of the 

 plate strongly impressed and depressed, with the apex slightly 

 recurved on the main portion of the cercus, the lateral section, which 

 is thrown into relief by the impressed and recurved sections, being 

 of the sub-falciform pattern found in the cerci of other species of 

 this group of genera, in which species, however, the cerci are not 

 at all lamellate, but instead show modifications of a simpler cereal 

 type; subgenital plate short, when seen from the lateral aspect 

 blunted, the apex strongly pinched dorsad. 



The male sex, and to a lesser degree one of the females, shows 

 certain color differences from the original description. The dorsal 

 coloration is appreciably marked off from the darker lateral bars 

 by narrow lines of dull yellow on the head and pronotum, which 

 are continued caudad from the pallid lines on the tegmina mentioned 

 by Bruner. There is also a dark bar, which varies in solidity, across 

 the ventral sections of the gense, lateral lobes and, more weakly, 

 the pleura, bordering ventrad the yellow described by Bruner. 

 The face is dull pale olivaceous green in both sexes. The caudal 

 femora are clear oil yellow proximad, passing to oil green distad, 

 with the distal extremity somewhat infuscated. 



The number of spines on the external margin of the caudal tibiae 

 varies from six to seven. 



Tetrataenia surinama (Linnaeus). (PI. I, figs. 24 and 26.) 



1764. [Gryllus] surinamus Linnaeus, Mus. Ludovic. Ulric., p. 146. [Surinam.] 



Igarape-assu. Five males. 



Para. (C. F. Baker.) One male, one female. 



This series shows the male sex to have a very great amount of 

 variation in size, and apparently to a certain degree locally in the 

 depth of general coloration; in the Igarape-assu specimens the 

 dorsal surface of the head and pronotum is fully as dark as the 

 lateral (i. e. ventrad of the narrow pale dorso-lateral lines) areas, 

 w^hile the tegmina are more olivaceous, instead of the same area 

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