10 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO3 



III. CARABOIDEA 



In this group adult Harpaliis caliginosus F., Carabidae (figs. 17, 

 18, 19), Tetracha Carolina (L.), Cicindelidae, and Lacoophilus sp., 

 Dytiscidae, were selected for study. The labral muscles are absent in 

 the three genera studied. In Harpalns the muscles of the cibarium 5, 

 6, and 7 (figs. 17, 19) and those of the dorsal and lateral pharyngeal 

 regions are similar to those found in Periplancta. Bar Y (fig. 19) is 

 attached to a subpharyngeal brace. The lateral dilator rnuscle of the 

 pharynx, ji (fig. 19), is not considered, necessarily, as a homolog of 

 57 in Periplancta or in any of the other species of Coleoptera since 

 it varies greatly in size, form, and position; but the function being 

 the same, it is given the same number. The place of origin of the 

 labial and hypopharyngeal muscles is unusual. In the anterior region 

 of the gula, caudad of the posterior tentorial pits there is a central 

 invagination, or apodeme (fig. 19, PTN), which is finlike and of 

 considerable size. The muscle of the hypopharynx, iq, the dorsal and 

 ventral muscles of the labium, 20 and 21 respectively, and muscle 

 21 A (fig. 19), arise on this apodeme and not on the tentorial struc- 

 ture as is the usual manner. It is possible that this apodeme represents 

 a greatly modified tentorial bridge and tentorial arms. The dorsal 

 muscle of the labium, 20 (figs. 18, 19), is inserted centrally on a pro- 

 jection that extends inward from the ventral labial wall in the basal 

 region ; it possibly performs the same function as muscle 20 in Peri- 

 planeta. Muscle 21 A (figs. 18, 19) was found only in this species; 

 it probably in some way supplements the action of the other labial 

 muscles. 



In Tetracha only the dorsal and ventral muscles of the labium, 20 

 and 21, respectively, and the muscle of the prcmentiim, 22, are pres- 

 ent; they arise centrally in the posterior gular region. The dorsal 

 dilator muscles of the cibarium, 5, 6, and y, are similar to those of 

 Harpalus; the compressor muscle group of the cibarium, 12, is more 

 strongly developed. The dorsal dilator muscle of the pharynx, 11, 

 is powerfully developed. The tormae of the labrum extend posteriorly 

 and then bend sharply ventrad to form a rigid lateral support on 

 each side of the mouth ; this rigid brace is continuous with the ventral 

 head structure. Bar Y projects from the posterior dorsal region of 

 this torma modification ; the vmscle of hypopharyngeal bar Y, 10, is 

 inserted on its distal end. 



In Laccophilus the ventral muscle of the labium, 21, originates in 

 the posterior gular area. The muscle of the hypopharynx, ip, is single, 

 broad, thin, and arises by means of a bifurcate tendon high on each 

 anterior tentorial arm. The compressor muscle group of the cibarium. 



