196 



THE UNIVERSITY SCIENCE BULLETIN. 



Color. Ventral aspect: White — the abdominal fringe of hairs, the 

 ventral abdominal tuft, the hair tufts before the hind coxae and those of 

 middle coxae — black. The hairs fringing the hind tarsi are smoky black 

 as are the middle and fore tibia. Eyes dark red. No indication of the 

 red pigment in the abdomen so conspicuous in older nymphs and adults. 

 White with the red eyes — the only conspicuous marking. 



Structural Details. The absence of the median abdominal carina 

 from the venter, as is the case also v^^ith N. undulata nymphs, is the 

 first and most striking peculiarity. The interspace betw^een the eyes is 

 large. Beak four-jointed as in adult. Tarsi all one-jointed, terminat- 

 ing in two claws. The spiny armature of fore legs is more generalized 

 than in later forms. The fringe of the hind legs confined to the margins 

 of the tarsi. 



The Older Nymphs. 



In order that space may be conserved, a table of measurements for 

 the various instars is presented below and a discussion of the changes 

 in structure as development proceeds appended. 



MEASUREMENTS IN MILLIMETERS OF NYMPHS OF B. MAROARITACEA. 



* Bueno gives length of species 6.7 to 8.1 mm.; lat., 2.23 mm. 



The adults of this species are separated in the synoptic table from 

 the other two species on the basis of the body length, which is greater 

 than 6 mm. This, with a diagnosis of the instars from structural 

 characters, may serve to separate the nymphs of this species from those 

 of the others. The table of measurements above is based on an average 

 of ten specimens of each instar. A larger number would be desirable 

 to obtain figures dealing with ratio of growth. The writer believes that 

 an examination of a sufficiently large amount of material would show 

 for head-widths and limb measurements a ratio of 1 : 1.25. That is 

 to say, the width of the head of the second instar nymph would be ap- 

 proximately 1.25 times that of the first Instar nymph. 



Upon attaining the adult stage a sexual dimorphism becomes appar- 

 ent. Besides the structural differences of the genitalia, the anterior legs 



