180 CALIFORNIA ACADEMY OF SCIENCES. 



those of the head and pronotum respectively, the former being 

 made to serve in subdividing the genus Keichenbachia. It 

 will be well to consider these sets of fovese in order. , 



During a recent collecting tour in Texas, I secured a large 

 series of a uniformly flavo-ferruginous species of Keich- 

 enbachia, belonging to the group in vvhich the male and 

 female antennas are difierent in structure. These specimens 

 were all taken in a very limited area, and are without the 

 least doubt of a single species. The males have the fifth 

 and sixth joints of the antennae elongate and swollen; upon 

 the occipital portion of the head there are two small, widely 

 distant, spongiose fove?e, but the apical fovea is completely 

 wanting. The females also have the same joints of the 

 antennae elongate and slightly dilated; the head has the 

 occipital foveas exactly similar in size and position to those 

 of the male, and in addition a third apical fovea, similar to 

 the others and equally pronounced. The male above noted 

 was described by Dr. LeConte as tumida; whether the 

 female has been described as a trifoveate species is a ques- 

 tion requiring further investigation. 



It is seen, therefore, that the presence or absence of the 

 apical fovea may sometimes be a sexual character, at least 

 in a certain class of species of which one is R. tumida, and 

 it is consequently of very little moment in a generic class- 

 ification, although the occipital fovete appear to hold a 

 very different position, and are evidently of more distinct 

 value. 



The pronotal foveas are very important from a generic 

 point of view, since they indicate great and radical differ- 

 ences, which extend throughout the body, and are evinced 

 by peculiar manifestations of sexual identity. For in- 

 stance, restricting ourselves for the present simply to the 

 American fauna, — those species having three small, equal, 

 punctiform fovei^, are the only ones which are subject to a 

 very decided sexual modification of the antennal club. 

 Those having three large, subequal, spongiose fove^e are, 



