39] THE HEAD-CAPSULE OF COLEOPTERA—STICKSEY 39 



on the meson, the mesal margins of the laminatentorium very frequently 

 are bent ventrad, producing a projection. Examples of this development 

 are seen in Calosoma (Fig. 446), Cybister (Fig. 451), Necrophorus (Fig. 

 460), Aleochara (Fig. 467), Heterocerus (Fig. 505), Dermestes (Fig. 511), 

 and Endomychus (Fig. 532). Genera that show the laminatentorium as 

 hardly more than touching on the meson are Peltodytes (Fig. 450),Scaph- 

 idium (Fig. 471), Neopyrochroa (Fig. 481), Noto.xus (Fig. 493), Psephenus 

 (Fig. 502), Cucujus (Fig. 520), Penthe (Fig. 542), and most of the Scara- 

 baeidae. The reduction of the laminatentorium takes place so gradually 

 that it is hard to tell when it has completely disappeared. There seems to 

 be no indication of it in Limulodes (Fig. 469), Collops (Fig. 478), Pseudo- 

 cistela (Fig. 536), Hyporphagus (Fig. 541), Sphindus (Fig. 547), and others. 

 In Tomoxia (Fig. 485), Pytho (Fig. 490), Alaus (Fig. 498), Tharops (Fig. 

 499), Throscus (Fig. 500), and others, there is no laminatentorium. The 

 pretentorial arms curve towards the meson and serve a similar purpose. 

 The laminatentorium of Tachinus (Fig. 460) and Epicauta CFig. 487) is in 

 the form of a lobe. That of Psephenus (Fig. 502), Dichelonyx (Fig. 550), 

 and Pelidnota (Fig. 551), possesses two long sharp cephalic projections. 



Arising from the dorsal surface of each pretentorium cephalad of the 

 laminatentorium and usually extending towards the dorsal surface of the 

 head is a projection of variable form, the supratentorium. Its generalized 

 condition would show a rather distinctly chitinized structure, with an 

 expanded ventral end that gradually narrows, then expands flat-like against 

 the ental surface of the head-wall. This kind of structure is found in a 

 very large number of genera, as all of the Adephaga except Peltodytes 

 (Fig. 450), the Hydrophilidae, Leptinus (Fig. 459), all of the Staphylinoidea 

 except Aleochara (Fig. 467), and Hister (Fig. 473), Pytho (Fig. 490), 

 Nosodendron (Fig. 513), Languria (Fig. 522), Megalodacne (Fig. 523), 

 Derobrachus (Fig. 519-), and others. The supratentorium is a surprisingly 

 persistent structure considering the large number of genera that possess 

 it in a more or less rudimentary state. The broken ends of the tentoria of 

 Eupsalis (Fig. 573), Lixus (Fig. 580), and Sphenophorus (Fig. 582), are 

 expanded, which expansion may include a part of the supratentoria. This 

 seems reasonable to believe when a rudimentary one is evidently present in 

 Rhynchites (Fig. 577) and Attelabus (Fig. 578). Sphenophorus is peculiar 

 in having the lateral margins of the tentoria fused to the oculata. The 

 head-capsule of this genus is suddenly constricted at this point, which 

 probably placed the tentorium and head-wall in contact, a fusion finally 

 resulting. The supratentoria of Cucujus (Fig. 520) and Passalus (Fig. 

 556) are stout structures, but extremely short. In the former, this condi- 

 tion is due to the flatness of the head, in the latter, to the unusually close 

 proximity of a part of the pretentoria to the dorsal surface. 



