10 ILLINOIS BIOLOGICAL MONOGRAPHS [242 



suture (Fig. 6, cs) on each lateral margin of the head. There is a distinct 

 precoila (Fig. 6, pel), in which a preartis articulates, located on each side of 

 the postclypeus meso-ventrad of the antennal fossa at the point of origin 

 of the clypeal suture. The vertex occupies all of the dorsal and lateral 

 parts of the head capsule not included within the fork of the epicranial 

 suture (Fig. 6, v). There are six ocelli (Fig. 6, oc), in two groups of three. 

 Each group is situated on the lateral margin of the vertex dorsad and 

 laterad of the lateral end of an epicranial arm. The antennal fossae are 

 located ventrad of the ocelli on the dorso-lateral margin of the vertex. 

 The large somewhat oval opening in the caudal aspect of the head is the 

 occipital foramen (Fig. 17, of). 



A primitive type of epicranial suture is found in the adults of Peri- 

 planeta and the larvae of Corydalis. The condition of the epicranial suture 

 in C. bivulnerus is very similar to that of these primitive forms, except that 

 the epicranial stem is not so long in proportion to the length of the epi- 

 cranial arms and that a portion of each arm is wanting near the antennal 

 fossae. This suture in Epilachna (Fig. 4, es) very closely resembles that 

 of C. bivulnerus, but the epicranial stem is much longer and extends almost 

 one-half the distance from the occipital foramen to a line drawn through 

 the antennal fossae. In Megilla the epicranial suture (Fig. 7, es) is present 

 but very short, not extending more than one-fifth the distance from the 

 occipital foramen to a line drawn through the antennal fossae; while in 

 Adalia, Anatis, Hippodamia, Coccinella, and Microweisea the epicranial 

 stem is not present and the epicranial arms diverge immediately from the 

 occipital foramen. In the adult larval stage of Hyperaspis the epicranial 

 suture is wanting, but it is present in the first instar. The epicranial stem 

 is absent in the second instar, but the epicranial arms are present; while 

 in the later larval instars the entire epicranial suture is wanting. The 

 adult larvae of Scymnus (Fig. 14) also lack an epicranial suture; no observa- 

 tions were made on the conditions present in very young larvae. 



The epicranial arms are present in most coccinellid larvae, but are 

 absent in the adult larvae of Scymnus and Hyperaspis. In C. bivulnerus 

 the epicranial arms extend ventro-laterad from their point of origin to a 

 point dorso-mesad of the antennal fossae. In Epilachna the epicranial 

 arms extend ventrad of the antennal fossae, but do not extend as far 

 laterad. In Chilocorus and Epilachna the epicranial arms are not widely 

 divergent, but in all of the genera of the Coccinellini they diverge widely 

 and become obsolete slightly ventrad of the antennal fossae. In the first 

 larval instar of Hyperaspis they diverge immediately upon the dorso- 

 cephalic aspect of the head, the epicranial stem being very short, and they 

 extend laterad almost parallel with the caudal margin of the head, make 

 an abrupt turn and extend laterad and ventrad to their point of obsoles- 

 cence. In Microweisea (Fig. 13) the epicranial arms diverge gradually 



