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the hind tarsi are bifid or appendiculate, and on this division 

 it will be necessary to furnish some notes, inasmuch as there 

 is wide diversity in the form of the claws which I call bifid, 

 and it is not difficult to arrange a series of Heteronycts in 

 such fashion that the appendiculate form seems to pass very 

 gradually to the bifid, requiring a definite statement (if the 

 terms are to be of value for identification of species) of exactly 

 what is covered by each term. If a species with typically 

 appendiculate claws be examined it will be seen that each 

 hind claw consists of two pieces — a basal compressed piece 

 (which approximates in form to a parallelogram) and a much 

 more slender apical piece attached to the external apex of the 

 basal piece. Transition from that typically appendiculate 

 build of claw to the bifid may be said to begin by a ten- 

 dency of the inner apex of the basal piece to be prolonged 

 more or less at an angle to the axis of the basal piece, and 

 that tendency becomes gradually in successive species nioj'e 

 pronounced until the prolongation becomes a well-defined 

 sharp process not much less than half the size of the whole 

 apical piece. When the point is reached of the prolongation 

 being more than a trifling prominence of the inner apex of 

 the basal piece (say, less than a quarter of the projection of 

 the apical piece) I call the claw bifid, as it then seems to end 

 in two processes not very greatly different in size. A varia- 

 tion of this latter form is found in some species where ^he 

 apical piece itself is extremely small and the inner apex of 

 the basal piece is produced like a triangular tooth scarcely 

 at all smaller than the whole apical piece. Next we find a 

 form in which the claw appears to consist of a single piece 

 ending in a sharp slender curved process and having a tooch- 

 like process projecting from its inner margin at a greater or 

 less distance from the base, and finally the genuinely bifid 

 form is reached where the apex of the claw is seen to be split 

 into two somewhat equal portions — usually both small. Thus 

 it will be seen that, in the following pages, an appendicu- 

 late claw is taken to be one having a basal compressed piece 

 of which the apex is more or less truncate, and the inner 

 apical angle not or very little projected, and a slender piece 

 attached to the external apical angle of the basal piece, and 

 that all other claw structure is regarded as bifid. It should 

 be noted that in many species of Keteronyjc the claws when 

 appendiculate look from some points of view as if they were 

 simple, and therefore require to be examined carefully. 



The shape of the labrum calls for close attention iu 

 discriminating the species of Heteronyx. This organ pre- 

 sents — I think in all the species — the common character of 

 being so formed that its dorsal surface may be regarded 



