247] THE LARVAE OF THE COCCINELLI DAE— GAGE 15 



Corydalis, but show a more striking resemblance to the conditions found 

 in the maxillae of carabid larvae. Though the coccinellid maxillae are 

 similar in form to those of Periplaneta or to those of the larvae of Corydalis, 

 they also show a great difference in structure and are much more specialized 

 than those of carabid larvae. In order to homologize the parts of the 

 maxilla, it was necessary to trace the development of this appendage from 

 the more generalized to the more specialized condition. In the tracing of 

 this development maxillae of the larvae of Carabidae, Lachnosterna, 

 Elateridae, and Curculionidae were found most useful. 



Each maxilla of C. bivulnerus is moderately large, slightly chitinized, 

 and consists of the following parts: a fused cardo and stipes, a palpifer, 

 a maxillary palpus, and a galea. The lacinia is apparently wanting. 



In the primitive type of coleopterous larvae the cardines are composed 

 of two sclerites; the subcardo, which articulates with the postcoila and a 

 second sclerite, the alacardo, which lies between the subcardo and stipes. 

 This condition is found in the larvae of Pterostichus and Lachnosterna; 

 while in the larvae of a curculionid beetle, Phytonomus, the subcardo and 

 alacardo are fused. A similar condition is found in the larvae of the Ela- 

 teridae. In the Coccinellidae the subcardo and alacardo are not only 

 fused to form the cardo, but the cardo and stipes are fused and the extent 

 of the cardo is only indicated by small and in many cases indistinct notches 

 along the sides of the fused cardo and stipes. This indication of the suture 

 between the cardo and stipes is found in the maxillae of all of the larvae 

 studied and there is but little variation shown. It will be seen from the 

 above that the stipes and cardo must be discussed as one sclerite. This 

 sclerite (Fig. 18, ss-\-ca) occupies the area at the proximal end of the maxilla 

 cephalad or ventrad of the gula. Its form in C. bivulnerus is that of a 

 rectangle. It is about as wide as long, slightly setaceous, and chitinized. 

 This general form of the stipes and cardo is found in all of the genera 

 studied except Microweisea, Scymnus, and Hyperaspis. In these genera 

 the stipes and cardo are narrow and elongated. In Microweisea and 

 Hyperaspis the proximal end is curved laterad. This curved portion 

 represents the cardo and the remaining part of the sclerite is the stipes. 



The palpifer is present as a distinct shoulder-like area (Fig. 18, pf) near 

 the distal margin of the fused stipes and cardo. Its form and position are 

 generally constant in all of the genera studied. This area bears at its 

 distal extremity the three-segmented maxillary palpus. The maxillary 

 palpus (Fig. 18, mxpl) is well developed in all of the genera. In C. bivul- 

 nerus they are stout and slightly chitinized. The first segment is cylindri- 

 cal, wider than long, and usually with one or two small setae. The second 

 segment is longer than wide and with one or two large setae. The third 

 segment is conical, about one-half as long as wide with two or three setae 

 and with a group of sensory organs at its distal end. The maxillary palpus 



