32 THE COCCIDAE 



difficult to separate them. When they are separated, which some- 

 times happens from the handling of the specimen, there is 

 frequently apparently less than four parts present, the actual 

 number. The usual number is apparently three. The mandibles 

 in such cases are separated from each other and from the maxillae. 

 They form two of the three parts and the closely applied maxillae 

 the third. They are normally all fastened together and form a 

 tube through which the liquid food is drawn into the pharynx. 

 This structure, formed of the closely applied mandibles and 

 maxillae, is the rostralis. It is frequently longer than the entire 

 body and may be five times as long. The rostrum serves simply 

 as a support for the rostralis and does not function as a tube 

 through which the food is drawn. The free end of the rostralis 

 in individuals which are not attached to their host-plant usually 

 does not project beyond the free end of the rostrum. The mandi- 

 bles and maxillae are lost at the first or second molt and are 

 wanting in the adult male. 



Crumena. — The thin cuticle of the head adjacent to the 

 proximal portion of the rostrum is deeply infolded or invaginated, 

 forming a long slender pocket which lies free in the body cavity 

 and generally extends through the mesothorax and metathorax. 

 The rostralis after its exit from the mouth extends into this pocket. 

 This pocket was first described by Mark and by him named the 

 crumena. It was later figured and described by Berlese who 

 designated it the giiaina delle setole rostroli. I had before the 

 name of Mark was discovered designated it as the theca. All the 

 slack of the rostralis is held in the crumena and the proximal part 

 of the rostral furrow is thickened and forms a sort of bumper, the 

 plena, against which the end of the rostralis rests. The crumena 

 has been observed in many coccids and is probably present in all. 

 It is difficult to identify in unstained specimens. The rostral fold 

 described by many .systematists is the portion of the rostralis 

 retained within the crumena. 



Endoskeleton. — There is a well developed series of chitinized 

 arms or bars present within the cavity of the head of all coccids. 

 These bars are a part of the endoskeleton and are usually desig- 

 nated as the head skeleton or chitinous cradle. The parts of the 

 endoskeleton serve for the attachment of the muscles that operate 

 the rostralis, rostrum, and the parts associated with them. In the 

 differentiation of species or genera, the parts of the endoskeleton 

 have not been used. There is only a slight variation in the form 

 and arrangement of these parts in the different subfamilies. 



