374 GEORGE H. CARPENTER AND MABEL C. MACDOWELL. 
more primitive than the legless grub ; that there must have 
been an increasing divergence between the imaginal and 
larval stages in the course of insect evolution ; and that such 
larvae as bee-grubs and maggots — apparently simple in 
structure— must be considered as the result of a long pro- 
cess of degradation. Some years ago this question of the 
divergence of imago and larva in the course of insect phyto- 
geny was discussed at some length by one of the authors of 
the present paper (Carpenter [ ’03 j ) . 
Recently several agricultural inquiries have supplied us 
with a number of the root-eating larvae of Dascillus cer- 
vinus. Neglected since the work of Erichson (’41) seventy 
years ago, this larva has during the past ten years been 
re-described by Boas (*96), Gahan (’OS), and the senior writer 
of this paper (’09, pp. 589-591, pi. lv). It seemed to us 
worth while to make a more careful study of the jaws than 
had previously been attempted, especially as the typical 
nature of the maxilla — in which all the parts of an adult 
maxilla are normally developed — must be regarded on the 
theory above mentioned as a primitive character. It is well 
known that in the vast majority of beetle larvae, even in 
typically campodeiform grubs like those of the Carabidae, the 
maxilla has undergone simplification, the lacinia being repre- 
sented only by a small bristle-bearing process. 
The well-developed maxillae of the Dascillus larva, then, 
encouraged us to look for other primitive characters m the 
mouth, and we paid particular attention to the tongue 
(hypopliarynx) and its associated structures. In the paper 
(Carpenter [’03]) mentioned above, attention was recalled to 
the pair of jaws — maxillulae — between the mandibles and the 
maxillae, which, well-developed in many of the Apterygota, 
are represented by Vestiges in some of the more primitive 
Exopterygote insects. The nature of these maxillulae was 
pointed out nearly twenty years ago by Hansen (’93), who 
laid stress on their presence as indicating relationship between 
the lower Insecta and the Crustacea., a view which we strongly 
support. These maxillulae are always associated with th e 
