ijQ L^Scptember, 



brownish-black ; very finely pale pubescent ; head, the first two joints of antennse, 



rostrum, and legs, reddish-testaceous ; pronotum reddish-brown, the disc brownish, 



unequal, in the middle somewhat sulcate, apical margin incrassated ; elytra, in the 



brachypterous form, very short, scale-like, black, exterior margin reddish-brown. 



Length, If mm. 



Scotland ; many short-winged specimens found among Sphagnum 

 in August, near Perth, by Dr. Buchanan White and myself. 



This species is probably mistaken for the brachypterous form of 

 H. pusillus, Fall., but the latter is, as far as I know, not dimorphous ; 

 it is larger, having the first joint of antennae much longer (nearly 

 twice as long as the diameter of the eye), reaching far beyond the 

 apex of the head. 



o 



Finland, Abo et Pargas : 

 1st July, 1877. 



ON STEIDULATION IN THE CICABIB^. 

 BY A. K. SWINTON. 



When we observe the upper surface of the first abdominal 

 segment of a male Cicada, the eye is arrested by two convex triangular 

 membranes (tymbals), placed laterally, of the consistency of parch- 

 ment, and traversed by elevated chitiuous ridges, which are indurated 

 centrally to correspond with a series of oblique callosities in the 

 membrane. These organs, resembling minute shells, are either exposed 

 or more or less covered by prolongations of the general integument, 

 and in the female are only denoted and rudimentary ; their function 

 is to effect by vibration the music of these insects, communicated, as it 

 appears to me, by scraping the indurated central part of their elevated 

 ridges (representing a lima), over a portion of the cavity in which 

 they are placed, projecting immediately posterior. 



Two theories are extant to explain the " drumming " of the 

 Cicadce. The one perhaps most commonly preferred, is derived from 

 dissections made by Reaumur (Mem., v, p. 1 ; ib. iv, p. 181 : 

 Amsterdam, 1741), who, not having seen the living insect, was led to 

 recognise several parts of the structure accessory to the tymbals as 

 engaged in the production of the sound. This view Messrs. Solier 

 and Goureau (who sought to confirm Reaumur's conception by obser- 

 vation and experiments on the Proven9al Tibicen orni, and Cicada 

 hcematodes, removing and tearing the various adventitious parts, 

 " ventral operculse," "mirrors," and "tender membranes" in succes- 

 sion) found it necessary greatly to modify, so as eventually and virtually 

 to localise the production of the sourM in the tymbals, which when 



