PEELIMINAKY CLASSIFICATIOlSr OF SCOLYTOIDEA. 197 



THE LARV^. 



The structural and morphological elements of the larvae of Den- 

 droctonus are shown in Part I, figures 39-43, and Plate VIII, figures 

 l-23j, and these, with the terminology and descriptions, wiU. serve 

 as a guide to a greatly needed further study of the larval stage 

 before we can have a basis for conclusions as to their importance in 

 taxonom}^. The writer has examined the larvae of quite a large 

 number of species, but no detailed study has been made except in 

 Dendroctonus and of the labrum of a number of species in other genera 

 (Hopkins, 1905, Plate I). This has been sufficient, however, to 

 indicate the wide range of variation in some of the elements and the 

 great importance of a more comprehensive knowledge of the subject. 

 In Dendroctonus the important characters are found in the eighth and 

 ninth abdominal tergites, and the front of the head. An example of 

 progressive modification is found in the sculpture and armature of 

 the eighth and ninth abdominal tergites from those without dorsal 

 plates in Division I and Division II, section a^, to the unarmed plates 

 of section a^ and to the armed plates of subdivision D, wfiich corre- 

 lates so nicely with progressively modified characters in the adults and 

 in the galleries. The larvae of the species of Platypus and Orossotarsus 

 examined by the writer show radical differences in form and in some 

 of the anatomical elements, as, for example, the labrum (Hopldns, 

 1905). 



THE EGGS. 



While the eggs of many species have been observed by the writer, 

 they have not been studied in detail. They appear to conform m 

 general to an oblong, oval, or nearly globular shape, and are pearly 

 white and smooth, with few elements of vestiture or sculpture to 

 serve as taxonomic characters. However, this is a subject worthy 

 of detailed study. The size of the egg in comparison with the size 

 of the abdomen varies enormously in different species. In a species 

 of CarpJiohorus a fully developed single egg was found to be so large 

 as to occupy almost the entire abdominal cavity. 



THE EMBRYO. 



The embryology of the scolytoid beetles is another subject which 

 has not received much attention. While the writer feels that there 

 is need of detailed study of the embryo to determine any additional 

 facts which may be of value, he is inclined to the belief that more 

 attention should be given to a comparative study and correlation of 

 characters of the postembryonic stages (young to matured larvae) 

 of a wide range of species in the order Coleoptera, in order that we 

 may know something more of the fundamental facts and be better 

 able to interpret their real significance. 



