DEVELOPMENT OF CASTES OF TERMITES. 39! 



nymphs with large brain and large sex organs (Fig. 8, a), and 

 (b) worker 1 nymphs, with small brain and small sex organs 

 (Fig. 8, b~). The long labrum is prominent in the nymphs of 

 both types. 



Nymphs 1.6 -i.8mm. long, with twelve antennal segments, 

 are differentiated into the "small-headed" and "large-headed" 

 types. 



Eutermes. 



E. morio Latreille. The eggs of this species of Eutermes 

 measure from 0.68 to 0.72 mm. in length and are slender and 

 reniform. The new r ly hatched nymphs are 1-1.2 mm. long; 

 they have eleven antennal segments, and they consist of the 

 large-brained reproductive type and the small-brained worker- 

 soldier type. 



E. sanchezi Holmgren. I have not seen the eggs of this species 

 but the newly hatched nymphs are very similar to those of 

 E. morio. They are 1.2 mm. long, with eleven antennal seg- 

 ments, and the tw r o types of reproductive and worker-soldier 

 nymphs are present. 



The newly hatched nymphs of E. morio and E. sanchezi are 

 almost identical in structure with those of E. pilifrons and are 

 therefore not figured; their later development has not been 

 studied, but there is no reason to believe that the three species, 

 which are alike in their early development, should differ in the 

 later phases. 



E. pilifrons Holmgren. The eggs of E. pilifrons measure 

 from 0.64 to 0.72 mm., and are slender and reniform (Fig. I, h}. 



This species was formerly described as E. rippertii (?) by 

 Knower, and I am indebted to Dr. Knower for my very abundant 

 material. Many of the nymphs have actually been dissected 

 out from their egg shells, so that there is absolutely no uncer- 

 tainty as to the structure or the size of the newly hatched forms. 



The newly hatched nymphs of E. pilifrons measure from 

 0.8 to 0.9 mm., the difference in length being due to whether the 

 nymphs are still in the curved embryonic position or have 

 straightened out. The number of antennal segments is eleven, 



1 The soldier caste is lacking in the genus Amitermes. 



