44 ILUXOIS BIOLOGICAL MONOGRAPHS [44 



surface, of compound eyes that are usually more or less emarginated, of a 

 ventral surface whose structures are practically in a similar condition, 

 and of a tentorium that is alike throughout, with the exception of the 

 Meloidae, in which the corpotentorium is absent. Though the dorsal 

 surface of the Mordelloidea resembles to a considerable extent that of such 

 families as the Carabidae and Cantharidae, yet this surface differs so 

 widely in closely related groups that we can hardly place too much impor- 

 tance on the resemblance here. What seems to be far more important 

 is the totally different condition of the ventral surfaces in the Mordelloidea 

 and the Carabidae, for instance. In the former the gular sutures and the 

 metatentorinae extend uniformly half way between the occipital foramen 

 and the submentum; in the Carabidae the gular sutures extend the whole 

 distance between these parts and the metatentorinae, nearly to the sub- 

 mentum. The Mordelloidea and such groups as the Adephaga and 

 Hydrophiloidea do not appear to be nearly related. 



The members of the Elateroidea are on the whole (Figs. 58-64, 206- 

 212, 351-357, 495-501) homogeneous with the exception of the Bu- 

 prestidae. The pretentorinae and the antennariae are located on the dorsal 

 surface, and the epicranial arms extend no farther caudad than the pre- 

 tentorinae. On the ventral aspect, the metatentorinae extend but little 

 cephalad of the occipital foramen, and the gular sutures no farther. The 

 corpotentorium is lacking in all except Cebrio and Euthysanius. In the 

 Buprestidae, on the other hand, the pretentorinae and antennariae have 

 migrated distinctly ventrad, and are not visible at all from the dorsal 

 surface. The gular sutures extend the whole distance between the oc- 

 cipital foramen and the submentum, and there is a distinct corpotentorium. 

 Considering these points, the Buprestidae are hardly closely related to 

 the rest of the Elateroidea. 



With the exception of the Georyssidae, the members of the Dryopoidea 

 (Figs. 65-69, 213-217, 358-362, 502-506) appear to be fairly homogeneous. 

 The chief characteristics are very prominent widely separated metaten- 

 torinae, located very near the occipital foramen, and a very broad sub- 

 mentum. The ventral surface of the Georyssidae, as represented by 

 Georyssus, is totally different. In this family the gular sutures extend 

 nearly to the submentum, and are confluent through practically their 

 entire extent. The metatentorinae cannot be definitely located. Georys- 

 sus would appear to be related to Hister, both through the condition of 

 the gula, of the tentorium, and of the dorsal surface. The general ap- 

 pearance of the ventral surface in the Dryopoidea is much like that of the 

 Elateroidea, and in other characteristics they are not unlike. These two 

 superfamilies are probably related. 



The representatives of the four families of the Dascilloidea (Figs. 

 70-73, 218-221, 363-366, 507-510) studied are similar in structure. There 



