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asymmetrical prothorax, ouly one side being carved down as nsual. The pronotnm 

 is transversely oblong in the American forms and one African species (PI. XIV. 

 fig. Ill), or is rounded at the sides and anteriorly more or less distinctly narrowed. 

 In all the Old-World species it bears anteriorly on each side a transverse row of 

 three or fonr long bristles. It is never evenly hairy all over, there being always 

 some naked spaces, whose extent differs often according to species. There is no 

 comb at the hind margin in the American Polyctenids, nor have any of our immature 

 Old-World specimens a pronotal comb, while all the adult examples we have seen are 

 provided with it, one new species (PI. XIV. tig. 10) even bearing a second comb of 

 short spines with a row of long bristles in front of the hind margin. The punctures 

 which Speiser mentions of the two species described by him {talpa and iidermediuii) 

 are jjresent in all mature forms, but are numerous in some and less so in others. 



The elytra are always fused together proximally, the slit which separates them 

 from one another posteriorly never reaching down to the base ; but there is always 

 an impressed line from the slit forward. They differ considerably in size and shape 

 in some of the species, being transverse in the American forms and as a rule ronnded 

 together, or each separately rounded at the side and apex in the Old-World species. 

 As in the case of the head and pronotum, some species have a comb, others are 

 without it, the American never bearing a comb of sjiines on the upper side. The 

 base of the elytra is concealed underneath the overlapping hind edge of the pronotum, 

 but is distinctly visible through the jironotum in specimens mounted in balsam. 

 Immature specimens have smaller elytra than adult ones, and the apical median 

 sinus which separates them is generally large with its extreme tip ronnded off, but 

 there is sometimes a sutural slit in nymphs as in adults (PI. XIII. fig. 8). 



The variety obtaining iu the outlines and armature of the pronotum and elytra 

 is etjualled if not surpassed by the diversity iu the development of the thoracical 

 stemites. There are two main lines of develojjment iu the underside of the thorax. 

 The forms with a transverse, more or less quadrangular, pronotum have the more 

 primitive sternal sclerites. The prosternum is triangular and does not extend in 

 between the coxae (PI. XIV. fig. 10), the apex of the sclerite either being obtuse (the 

 African species figured) or more pointed (the American Polycteaids). Behind the 

 fore coxae the endoskeleton (apophysis) is distinctly visible. In the second type, 

 to which all the Old-World species belong with the exception of the new African 

 s])ecies figured on PI. XIV., the prosternum is longer, being produced into a pointed 

 or obtuse process which extends in between the fore coxae (PI. XII. fig. 4, XIII. 

 fig. li) and nearly touclies the mesosternum. This iutercoxal process is not essentially 

 different in adult and immature si)ecimens of the same species. The mesosternum 

 is transverse in the American forms, anteriorly somewhat excised and posteriorly 

 truncate. The metasternum is contiguous with it, and resembles an abdominal 

 sternite except in extending forward laterally to the midcoxal acetabulum. 

 PI. XIV. tig. 1 1 represents a similar type inasmuch as the metasternum is transverse, 

 but this type differs very much in the shape of both the meso- and metasterna, the 

 latter sclerite being small, not reaching the sides of the metasternite, and being 

 separated from the mesosternum by a membranous interspace. Moreover, the 

 episternum of the metasternite, instead of being nearly sipiare, as iu the American 

 roli/ctcnidue, is transverse. The other species, some occurring iu Africa and others 

 in Asia, also have two distinct types of meso-metasterna, one of which is illustrated 

 by text-tig. 2. Here the mesosternum (Ms) is anteriorly more or less rounded and 

 convex, and the suture sejtarating it from tlie metiislcrnum is straight and lies 



