I04 PRESIDENTIAL ADDRESS SECTION D. 



to trembling through fright in mammals, and, if so, we could 

 assume that the same environment has produced the same nerve- 

 tone in both termites and termitophiles. 



6. The Relationship Between the Number and Character 

 of the Termitophiles and the Social Life of the Termite zmth 

 which they occur. — The mode of life and general characteristics 

 of different species and genera of termites, of course, differ, and 

 it would be of great interest to trace the resulting effect on the 

 various termitophiles. 



Among parasites in general we seldom find the same 

 identical species of parasite in different host-species ; it does 

 occur, but it must be regarded as exceptional. Similarly, except 

 in the case of some dubious termitophiles, the same species of 

 termitophile is not very often found associated with more than 

 one species of termite. 



Thus, although Ternies vulgaris Havil. and Tcrmcs latericius 

 Havil. are closely similar to each other in external morphology, 

 and they are both fungus-growers, and their nests occur in close 

 proximity, yet the Termitoxenia, which may be found in both of 

 them, belong to different species. 



On the other hand, allied termitophiles exhibit some tendency 

 to occur in the nests of similar termites, but the relationship 

 is not at all clearly defined. 



Thus, the dipterous larv?e with jointed processes, from the 

 Transvaal and Madagascar, both occur in the nests of Micro- 

 ccrotcnnes. The two known species of termitophilous tineid larvae 

 both occur with Rhinotermcs. The peculiar and highly modified 

 flies of the family Phonidcc all occur, as far as I am aware, in 

 the nests of Termes. Nevertheless, marked exceptions may be 

 noticed ; for example, we find highly modified physogastric 

 staphylinids in the nests of fungus-growers and in those of 

 non-fungus-growers ; also the two quite similarly modified isopnds, 

 Phylloniscus and Termitoniscus, are found, respectively, in the 

 galleries of Hodotermes in the Free State and in the nest of 

 Termes bellicosus in West Africa. 



It should be noted in this connection that teniiitophiles tend 

 to exhibit such striking differences in their morphology that 

 systematists have founded a great number of mono-typical genera. 

 The same phenomenon, but in a less striking form, is seen, for 

 example, in bird-lice. Every species of bird tends to have its 

 own species of louse, but in this case the morphological differences 

 are not so great as to lead to the creation of a new genus for 

 nearly every species. 



The great majority of the described termitophiles occur in 

 the nests of the species belonging to the large and specialised 

 genera Termes and Enltermes. Very few have been described 

 from the nests of the more primitive genera CaJotermes, Leuco- 

 termes, and Coptotermes. For example, in South America the 

 species of Ternies and Eutermes comprise less than 70 per cent. 



