DEVELOPMENT OF CASTES OF TERMITES. 397 



MESOTERMITID.E 



A rrhinotermes simplex. 

 Reticnlitermes flavipes. 

 virginicus. 

 n. sp. 

 METATERMITID^E 



Anoplotermes fumosus. 

 Amitermes tubiformans. 

 Eutermes morio. 

 sanchezi 

 pilifrons. 



1. The eggs of these termites are largest in the primitive forms, 

 the Protermitidae, measuring from 1.2 to 1.7 mm. in length, 

 they are smaller in the Mesotermitidae, from 0.68 to I mm. long; 

 and are smallest in the Metatermitidae, from 0.56 to 0.72 mm. 

 long. 



2. The newly hatched nymphs correspond in size to the eggs 

 from which they have hatched. 



3. The newly hatched nymphs are externally all alike, but 

 they are differentiated by internal structural characters into 

 two clearly denned types : (a) the reproductive, or fertile forms, 

 with large brain and large sex organs, and usually a dense opaque 

 body; and (b) the worker-soldier, or sterile forms, with small 

 brain and small sex organs, and usually a clear transparent body. 



4. At the time of hatching the antennae of the Protermitidae 

 (Calotermes n. sp., Cryptotermes cavifrons, and probably also 

 Termopsis angusticollis and Neotermes castaneus) have nine seg- 

 ments, with the third segment entire; those of the Meso- 

 termitidae (Arrhinotermes simplex, Reticulitermes flavipes, R. vir- 

 ginicus and R., n. sp.) have nine segments with the third 

 subdivided; those of the Metatermitidae (Amitermes tubiformans, 

 Eutermes pilifrons, E. morio and E. sanchezi, and probably also 

 Anoplotermes fumosus} have eleven segments, the third subdivided. 



5. Nymphs with a body length of about 2 mm., or 2.5 to 3 mm. 

 in the larger genera, are differentiated into "small-headed" but 

 large brained reproductive forms, and " large-headed " but small- 

 brained worker-soldier forms. 



6. The worker-soldier nymphs of Eutermes pilifrons, 2 mm. 



