NO. 1 GST. THE THORAX 01' INtSlJUTtS—tSNODURAlSl^. 5g3 



epislornuin {Epx) oftiMi (li\ ided into scNcral parts by vertical rulj^es 

 or lines (102, 100). 



5, Metatlioracic pleurites horizontal or nearly so (110-121). Wing 

 process ( WP) a prominent oblique arm. arising from anterior ends of 

 pleurites, lying just behind and parallel with a similar arm from the 

 preparapteruni which also lakes part in supporting the wing. (See 

 description under 8.) Usually a more or less prominent suprae- 

 pimeral plate present (111-121, epiit) to which the ends of the meta- 

 pseudonotum are connected. 



G. Trochantin {Tn) present in prothorax and mesothorax, but is 

 usually a small sclerite at base of coxa (1)!), 104) concealed in coxal 

 cavity formed by projecting pleurites. In Silphidae (100) and Bu- 

 prestidie (100) it is exposed on surface of mesothorax. Lacking in 

 metathorax. 



7. Only one i^'eparapterum {P) present in either segment. Post- 

 'parajDterum lacking. Preparapteruni of mesopleurum usually a small 



l^late or rod lying before the wing process (102, 103, 107, 108). 

 Sometimes it bears a ])ronator muscle disk (101, P, PD). 



8. Preparapteruni of metathorax in most beetles fused with an 

 anterior subdivision {cps) of episternum {Ep.s) as in Cyllcne and 

 DendroctonuH (IK), 118, /'-)- eps), making, with the wing process 

 ( ir/*) , two conspicuous wing-sup^iorting arms. In lower forms, like 

 Galosoma (110, 113) and Dytlscus (11-1, 115) the parapteruin (F) 

 and its disc {PD) are entirely free from the episternum {Eps) though 

 closely articulated to front of wing process {^VP). Other forms, 

 such as Ilydi'oph'dus (111, 112) and Melolontha (117, 121), show an 

 intermediate condition in which the line of fusion is distinct. 



0. Mesonotum (125, 127, 128, 120) generally presents a triangular 

 scutellar area between bases of elytra. Mesopseudonotum lacking 

 unless represented by two small plates (127, 128, 131, q) connecting 

 mesonotum with metanotum. 



10. Metanotum in lower families like Carabidte (132) and Dytis- 

 cidae (13G) distinctly divided into three transverse parts (/>«<", set, 

 scl). The first or prescutum (132, 130, 'psc) carries the prophragma 

 (Aph) and the anterior notal wing processes (ANP) ; the second 

 or scutum (scf) is divided transversely into an anterior and a pos- 

 terior plate by a large transverse ventral ridge (133, 137, ^v) peculiar 

 to the Coleoptera and forming lines (132, 13G, w) on the surface, 

 wdiile each of these is divided again into separated lateral regions 

 by a median interlocking of the pre.scutum (psc) and scutellum (-s'C'Z). 

 Thus the scutum consists of four well-marked subdivisions, the 

 posterior pair of which carries the posterior notal wing processes 

 (PWP). The scuttellum (scl) consists of a median triangular area 

 produced into a tongue on the floor of the median notal groove {^r), 

 formed by the entodorsum or ventral V-shaped ridge (133, 137, F), 



