124 CAROLINE BURLING THOMPSON 



Lespes describes the origin of the soldier of L. lucifugus in 

 the following words: 



Les ouvriers et les soldats ont line organisation presque identique; 

 on pourrait dire que les deux formes ne different que par les mandibles 

 et leurs muscles; de plus, ils subissent en meme temps leur derniere 

 metamorphose depiiis le 20 juin jusqu'aii 20 juillet. Ainsi que je 

 dirai plus loin, j'ai vu cette transformation s'effectuer sous mes yeux; 

 avant qu'elle soit terminee, il est impossible de savoir s'il va naitre 

 un soldat on un ouvrier. La nymphe qui leur donne naissance est 

 en tout semblable a un ouvrier sauf la taille. 



The origin of the soldier caste in L. flavipes and L. virginicus 

 is described as follows by Snyder ('13, '15). During August, 

 nymphs that in external appearance were worker-like (with 

 large rounded head, mandibles with marginal teeth, and broad 

 labrum), were found in the quiescent stage that precedes a molt. 

 The molt was observed and the newly emerged forms were 

 identified as young soldier nymphs by the characteristic pointed 

 mandibles without marginal teeth and the slightly elongate or 

 oval head. Snyder further states that these newly molted 

 soldier nymphs have fourteen antennary segments, and that 

 the body length is over three millimeters in L. virginicus. 

 The length of the newly molted soldier of L. flavipes was not 

 stated, but it is probably between three and four millimeters 

 in the larger species. Through the courtesy of Mr. Snyder I 

 have examined the mounted heads of these newly formed soldier 

 nymphs and have noted the presence of a large clearly defined 

 frontal gland, which proved that internal characters are already 

 present and are probably recognizable in those antecedent worker- 

 soldier forms which are to become soldiers; those which are to 

 become workers having in all probability the smaller primitive 

 frontal gland characteristic of the adult worker. 



With these facts in mind a late differentiation of the generalized 

 worker-soldier type of L. flavipes was to be expected, and I was 

 not surprised to find this type still generalized and undifferenti- 

 ated at the end of the first stage of development. From the 

 embryological standpoint also it would be probable that the 

 more highly specialized coenogenetic soldier type would appear 

 late in the ontogeny. 



