76 PARTIAL ORISMOLOGY. 



corneous ridge. The prothoracic case is thereby divided into two lateral 

 halves (for example, in Gryllotalpa, PL XI. No. 1, f. 3, c). Sometimes 

 the upper surface projects in a similar central pectinated ridge, as in 

 many of the genus Gryllus, Fabr. (Acridium, Latr.) Besides its Disc 

 (discus) and MARGIN (margines), we distinguish upon it the surrounding 

 BORDER (limbus^). Between this pronotnm and the anterior sternal 

 plate we find on each side in the cursorial ( Carabici) and natatorial 

 beetles (Hydrocanthari),a distinct corneous scale, which, as the muscles 

 of the coxae originate at them, should be called shoulder-blades; and, 

 that we may distinguisli them from the larger shoulder-blades of the 

 intermediate legs (which have been long called scapulae}, may be called 

 the smaller or anterior shoulder-blade (pmium*}. It is a flat, more or 

 less heart-shaped plate (PI. IX. No. 1 fig. 4, of Carabus, No. 2, fig. 4, 

 Dytiscus), and which forms the posterior portion of the sides of the 

 prothoracic segment, and is contiguous in front to the wings of the 

 proste.rnum, which extend upwards to the pronotvm. Its superior margin 

 turns inwards (the same b*), and forms a broad, bowed corneous 

 ledge, thus presenting a still wider surface to the muscles of the coxae, 

 upon which they may spread themselves. In Buprestis, which has 

 this margin very broad (No. 3, fig. 1, A, A), I found upon its posterior edge 

 a small round corneous plate, which was distinct from it (the same b, b), 

 which upon the opposite side was contiguous to the prosternuin, and is 

 doubtlessly the analogue of the anterior shoulder. I have not observed 

 it in other families of the beetles, in which the turned margin of the 

 pronotum takes its place (PL X. No. 3, fig. 1.) 



The inferior plate, the PROSTERNUM (PL IX. &c. B, B), has much 

 more limited dimensions than the superior. It is less flat, rather 

 inclining beneath to an angle, the edge of which is frequently prominent, 

 or not rarely prolonged into a mucro posteriorly (Elater). Close to the 

 central ridge the SOCKETS (acetabula) of the anterior legs are seated, 

 one on each side ; in front the articulating membrane is affixed, and 

 posteriorly the membrane which connects it with the mesothorax. The 

 SPIRACLE of the prothoracic segment is found here ; it is a longitudinal 

 gap surrounded by a callous margin, into which the tracheae of the 

 anterior part of the body open themselves (PL XI. No. 1, fig. 2, a, a). 

 In all those families to which this division of the prothoracic case is not 



' The Latin language has no diminutive of scapnln, we have therefore derived it from 

 the (.<reek, in which language u>/j.iov signifies a small shoulder. 



