46 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



iSC 



Fig. 7. — Antennal organs of a water beetle, Dytiscits marginalis, copied from 

 Hochreuther (^5). A, longitudinal section through a hollow pit peg (HPPg) ; 

 B, longitudinal section through a small massive pit peg (MPPg) and 2 pore 

 plates (PP). This drawing is a combination of Figs. 32 and 58 from Hochreuther, 

 slightly modified. C, a small tactile hair from first segment, total preparation ; 

 and D, portion of Fig. 12 from Hochreuther, showing 4 small sense bristles 

 from second segment. NP, nerve fiber ; SC, sense cell ; SCG, sense cell group ; 

 and SP, sense fiber. 



Fig. 8. — Portion of left elytron (A and B) and left wing (C) of Mexican 

 bean beetle, showing position of olfactory pores as indicated by numbers i to 4 

 and letters a to d on dorsal surfaces. A shows relative sizes of peduncle of 

 elytron and group / when compared with size of basal margin (BM) of elytron; 

 A and C, X 12 ; and B, X 67. The lower side of A and B is the outer margin 

 of the elytron. C, costa ; MD, muscle disk ; Me, media ; R, radius ; RP, radial 

 plate; Sc, subcosta; ScH, subcostal head. 



