290 CLAUDE FULLER. 



beyond H take place the oi"gan will, by progressing to Kb 

 through J^ become one of XVII joints. 



Development. — The condition ab ovo (fig. 13, g) may be 

 regarded as one of VIII progressing to X, as in (/). This 

 becomes XII as in (e), and this XIV as in {h). (Figs. 13, d-g, 

 are in proportion.) 



(10) Psammotermes allocerus 8ilv. Fig. 14 a-w. 



Antennal Index. — Imago XVI ; soldier XVI to X ; worker 

 XVI to XIV (XVII). 



This is essentially a desert termite ' presenting many 

 peculiarities, some of which at least may yet be traced to its 

 evolution in fitting itself to the conditions of an adopted 

 environment. 



The imagos are small ; bulk for bulk they are larger than 

 the rank and file of the community, but there are always 

 a good many soldiers larger, and a small percentage 

 particularly so. 



The workers do not attain a distinct adult appearance, 

 but this seems only because they do not become strikingly 

 pigmented. Their colour is cream compared to the milk 

 white of the immatures. There is no special caste distinction, 

 and they range from small to large in a finely graduated 

 series. A few workers are comjjaratively large, but not 

 bulkier than the imagos. 



The soldiers are extremely variable in size ; the smallest 

 lesser than the imagos, the largest greater. As with the 

 workers they also intergrade finely with a few which seem 

 exceptionally large, as against the majority in a given nest 

 series. This is brought out in the following table of 67 head- 

 widths for one nest series, as in this species the head-width 

 of the soldier is closely in proportion with the length and 



' Holmgren, Nils ('' Termites from Natal and Znliiland." ' Entomol. 

 Tidskrift,' Arg. 34. Haft 2-4) reports Psammotermes fuseo- 

 fenioralis SjostecU, a species of tlie littoral of the Red Sea, as being 

 obtained by Ivar Trag&rdli in 1905 at Lake Sibayi, in Zululand. This 

 record as regards the locality needs confirmation. 



