122 ENTOMOLOGICAL NEWS. [April, 'c"J 



there tapered evenly to the apex. From the side it may appear 

 pointed as in canicularis, pi. Ill, fig. 5; or capitate as in mar^i- 

 nata, fig. i ; or subapically dilated as in davisi, fig. 4. In 

 similaris, fig. 9, it has two spinelike processes on the under side, 

 which together show as one from the side. An extreme form 

 from Mexico (sp. indet.) is represented in figures 7 and 8, 

 where it takes the form of a pair of curved horns. The large 

 side pieces also show some difference in shape, though less 

 than in the uncus. 



The opercula afford good characters. Usually they vary 

 but little, the single instance of great variability being in 

 canicularis, which merges into the opposite extreme of linnci. 

 Even the color of these structures is of some importance. 



The first and second abdominal segments below are in- 

 timately united and appear almost as one, the first bordering 

 the anterior margin of the second. Taken together they differ 

 considerably in the various species, the greatest variability in 

 any one species again showing in canicularis. The figures of 

 linnci and canicularis, pi. IV, figures 7 and 8, though drawn to 

 one scale, represent large and small specimens, respectively- 

 the average size of each species with size eliminated, the dif- 

 ference is not as great as at first appears ; consequently, the 

 amount of variation needed to bring the two forms together 

 is not really so great. The last ventral abdominal segment, 

 used by Davis and Joutel in their separation of linnei (tibiccn), 

 canicularis and sayi (pruinosa), are also of value. 



The thoracic sclerites offer practically no differences in shape 

 within generic limits. We have lettered these sclerites (pi. IV, 

 fig. i), using pruinosa for this purpose, but the result is not 

 entirely satisfactory and some changes may have to be made. 

 The prosternum lying between the front coxae is hidden beneath 

 the lower part of the head. The mesosternum is a large, 

 broadly pentagonal sclerite, just anterior to and partly between 

 the second pair of coxae. In the prothorax, the large lateral 

 pieces, immediately posterior to and at the sides of the front 

 coxae, are an inflexure of the pronotnm. The two small scler- 

 ites posterior to it represent the propleural sclerites the proe- 

 pisternum and the proepimeron. Both pleural pieces of the 



