MUTILLID^E. 259 



Cresson l describes the wings as " dark fuscous, paler at apex " ; but in the Mexican 

 example I refer to his species they are not paler at the apex, but decidedly paler at 

 the base in front of the basal nervure. This specimen has the head and thorax covered 

 densely with long white hair ; the pronotum finely and closely, the mesonotum much 

 more strongly, punctured, the punctures on the latter more widely separated, the 

 extreme base of the mesonotum being impunctate ; the scutellum punctured like the 

 mesonotum ; the median segment coarsely and irregularly reticulated ; the abdomen 

 sparsely covered with long white hair ; the legs densely covered with white glistening 

 hair ; the second recurrent nervure received quite close to the base of the cellule. 



Fam. MUTILLIDJE. 



This well-marked family, one of the most extensive of the Aculeata, is well represented 

 in our region. Its chief peculiarity is that the females are apterous and the males 

 winged. This fact, coupled with great differences in other respects, in the absence of 

 direct observation makes the uniting of the sexes a work of very great uncertainty, and, 

 in truth, I do not see how it is to be accomplished from the mere comparison of cabinet 

 specimens. In Mutilla proper I have only been able to unite the sexes to my satis- 

 faction in one instance, and this I have done on the direct observation of Mr. H. H. 

 Smith, who has noted the male and female of Mutilla cyllene. The difficulty is further 

 increased by the males (and this is true of Mutilla and Sphwrophthalma, and of the 

 former, at least, in most parts of the world) having a certain type of coloration in com- 

 mon, namely, black bodies and legs, with a ferruginous abdomen and fuscous or blackish 

 wings, and with, on the whole, a general agreement in punctuation and clothing of the 

 body. This general resemblance of the males not only makes their specific determination 

 a work of difficulty, but it adds greatly to the task of assigning to them their respective 

 partners of the opposite sex ; it is, in fact, impossible to do this in many cases in default 

 of direct observation on the living insects, and I have therefore had to describe most of 

 the males as distinct species, although I feel satisfied that they are connected with 

 females that I or other Hymenopterists have already described under different names. 

 The males, as species, are not difficult to separate, even if they do agree closely in 

 clothing and coloration, by the keels &c. of the pygidium and hypopygium, for I find 

 that in these parts each species shows distinctive peculiarities. Unfortunately, hardly 

 any of the authors who have described American Mutillidse make any mention of this 

 most important structural feature. The form and structure of the internal genital 

 armature is another prime factor in specific definition ; but, of course, it is not of such 

 easy application as the form of the terminal abdominal segment. 



As regards the males (and the same remark might almost equally well be applied 

 to the females) the following points should be noted in specific descriptions : — The 

 form, clothing, and sculpture of the scape, and the relative lengths of the third and 



2ll2 



