6 BULLETIN 108, UNITED STATES NATIONAL MUSEUM. 



As in most groups, no one genus is more primitive in all its charac- 

 ters than other genera. As far as venation is concerned Mastotermes 

 is the most primitive; among our genera Termopsis is the most 

 primitive for venation, cerci, and gula. However, Kalotermes is 

 more primitive in possessing ocelli; both lack a true worker caste. 

 As we progress to the more highly specialized forms we find the gula 

 becoming shorter and proportionally broader, the castes more differ- 

 entiated, the soldiers more specialized (nasuti), the legs often shorter 

 and weaker, the wing-scales smaller, the clypeus longer and more 

 distinctly bilobed, the pronotum smaller and more diamond shaped, 

 the abdomen more cylindrical, and the wings without reticulation. 

 These highly specialized forms have opaque wings with ciliated mar- 

 gins. The opening of the frontal gland — the fontanelle is a character 

 peculiar to certain forms; it therefore furnishes a good basis for 

 primary division. The Rhinotermitinae, by the absence of hair on 

 wings and by the reticulate venation, show affinity with the Kalo- 

 termitidae; but by the fontanelle. bilobed clypeus, and reduced 

 costal venation they are allied to the Termitinae. 



DISTRIBUTION. 



Termites are widely distributed over the w^orld, but as compared 

 to the enormous number of individuals of the different castes in the 

 social communities or nests there are but relatively few species and 

 genera. Termites can be traced back in geological times to the 

 tertiary age. (Handlirsch, 1908.) 



Wliile generally associated with the Tropics, termites are by no 

 means restricted to tropical countries. In the United States probably 

 species occur in every State in the Union. They occur as far north 

 as Quesnal Lake in the Caribou Provincial Electoral District in 

 British Columbia (Termopsis angiisticollis Hagen or nevadensis 

 Hagen), on Vancouver Island, British Columbia, and in Washington, 

 Idaho, Montana, and Maine. Hence in America termites occur as far 

 north as latitude 52° 30'. Furthermore, these insects occur at high 

 altitudes in the Rocky Mountains and Pacific Coast Range, elevations 

 of 7,000 to 8,000 feet being reached. 



Scudder (1884) in an article entitled The Fossil Wliite Ants of 

 Colorado writes that the composition of the white ant fauna of the 

 ancient Florissant, to which locality the known American fossils are 

 confined, differs considerably from that of tlie localities known in 

 the European tertiaries. In the fu-st division ^of the Florissant 

 temites, the genera Parotermes and Hodotermes occur, which are now 

 represented by living types. In the second division, -species in the 

 genus " Eutermes" are found. Species of Nasutitermes (Eutermes) 

 and Constrictotermes at present occur only in the southwestern States. 



1 Genera with a branched scapular vein. 2 Genera with a simple scapular vein. 



