88 



Psyche 



[June 



but a true homology, the mandibular pillar of Thysanoptera being 

 formed in a similar manner, but the sulcus closes up more com- 

 pletely; the relationship of the maxillary seta to the maxillary 

 plate is identical in the two orders.^ 



One of the latest works on the mouth-parts of Homoptera that 

 we are acquainted with is the interesting memoire by E. Bugnion 

 and N. Popoff.- These well-known savants have studied the sub- 

 ject from the adult stage and come to some slightly different con- 

 clusions than those reached by us from a study of the embryo. 



14a to g. Successive vertical sections through head of Plata; a, the most ante- 

 rior; g, the most posterior. 



In conclusion we find that: 



(1) The mandibles and maxillary arise as in other insects, the 

 former being articulated in an approximately normal position. 



(2) The Homopteran and Heteropteran mouthparts arise and 

 develop in the same manner. 



'In a species of Thrips (Tubiilifera) from Larat the young develop in the uterus of the female 

 and are born fully developed. In some young embryos taken from a dried specimen of one of 

 these there appears to be a seta on the right maxillary plate as well as on the left, which become 

 aborted at a later stage. Our specimens were old and the evidence not rehable but the point 

 is worth noting. 



'Ann. Sci. Nat. 9' S. Zool. 1910. 



