564 PROCEEDINGS OF THE NATIONAL MUHEVM. vol. xxxvi. 



and of two slender lateral strips forming the posterior margin of the 

 notum and ending in the axillary cords {AxC). 



This simple Calosoina-Dytiscus plan (132, 136) is distorted by 

 modifications in the higher families, but a serial change can be 

 traced through HydrophUi/s' (134), Melolo7itha (135, 138), and 

 CyUene (140). 



11. Pseudonotum of metathorax {PX) Avell developed in all beetles 

 (132-137, 139, 140), carrying the postphragma {Pph) and articulat- 

 ing by its extremities (/) with epimera of metathorax. Absent in 

 Coleopteran puj)8e (122, 123). 



12. Elytra {El) articulated to mesothorax by the ordinary three 

 axillary sclerites, though the first and second are sometimes fused 

 (127, 128). 



13. Wing bases of usual construction (11)2, 193, 194, 195, 198). 

 Head of the costa (6') frequently separated from main shaft of the 

 vein (197) and attached to the subcosta {Sc) by a process fitting into a 

 cavity in the head of the latter. Venation poorly developed (196). 

 Axillaries normal, sometimes with a small accessory piece (199). 



X. NKUKOPTEKA. 



Species studied. — CorydaJls cornuta (142, 143, 144, 145, 147, wing 

 bases 200, 201). 



Clianieterlstlcs. — 1. l*osterior seguient of gula projects beyond rim 

 of head and is entirely surrounded by membranous sutures, thus 

 strongly suggesting a microthoracic origin. Between head and 

 prothoi'ax is a wide collar-like band open dorsally, mostly concealed 

 within rim of pronotum. Perhaps this collar is microthoracic, but 

 possibly it is presternum of prolhorax. 



2. Prothorax elougate, depressed. Xotunf and sternum separated 

 by wide infolded pleuro-tergal membrane. Pleurites reduced to small 

 plates, episternum fused with steruum. l*rocoxa simple, cylindrical, 

 not double as in meso- and metathorax. 



3. JNIeso- and metanotum sufficiently shown b}' tigs. 142 and 143. 

 Both notal Aving processes carried by scutum. 



4. ]Meso- and metapleurum of the adult similar (147). One prep- 

 arapterum (P), fused with episternum. Trochantin {in) large. 

 Coxa of two parts, a ventral segment {(Jx) carrying the trochanter, 

 and a dorsal posterior segment {epm). A stud}' of the pupa (145) 

 and the larva (144) shows that the upper coxal segment is simply 

 a detachment of the epimerum {FJ pm) fused upon the coxa {Cio). 

 In the larva (144) epimerum is divided {Epm, epm) ; coxa {Cx) 

 is simple, as in prothorax of adult. In jjupa (145) lower subdivision 

 of epimerum {eps) extends downward and attaches to rear side of 

 coxa. In adult (147)' this separation completed and lower plate 

 (epm) of epimerum {Epm) entirely detached from the latter and 

 intimately fused with coxa. 



