24 RKVISIOX OF THE AMYCTERIDES, vi., 



tubercles of the row being generally all conical, though the posterior ones are 

 larger; the third row is situated on the basal portion of the seventh interstice and 

 may be represented by only one or two tubercles. The humeral tubercle belongs 

 neither to the second nor third rows, being situated at the confluence of the fifth 

 and seventh interstices. The other interstices bear no tubercles, except occa.siou- 

 aUy the posterior portion of the second; while the fourth and sixth are only trace- 

 able with difficulty. The sides are more or less infiexed and the interstices granu- 

 late, often obsoletely, above. The ventral surface is plane in the male or lightly 

 transversely convex, with the basal segments somewhat depressed ; in the female 

 the abdomen is convex autero-posterioi'ly and transversely. The anterior coxae 

 are subcontignous, almost, but not ([uite, touching. The tibiae often possess 

 characters, generally sexual, of specific importance. The anterior tibiae are for 

 the most jjart unifonn in structure except in ,4. denticollis whei'e there is a deep 

 subapical emargination in the male. The intermediate tibiae possess sexual 

 characters in many species in the form of a deep sul)apical emargination. The 

 corbels of the posterior tibiae require a rather fuller description ; these are more 

 or less oval, with an anterior extension somewhat triangular in shape, and gen- 

 erally inclined at an angle to the plane of the rest of the corbel. The setae sur- 

 roimding the corbel are internipted at the extension which generally has a few 

 setae more irregularly arranged or in clumps. This extension varies much in 

 development, sluijjc. and degree of development in the buttress which supports 

 it from the anterior surface of the shaft; these variaticms may be sexual, as in 

 A. scabro.'ins, but generally the characters are similar in both male and female. 

 The posterior tai-si are nuire or less elongate, but shorter and l)ri)ader in some 

 species than in others. 



Dissections have been made of the male genitalia in several species. These 

 have shown that the structures do luit differ fundamentally, though showing varia- 

 tion in the shape of the median lobe and in the form of the internal sac. I am 

 deeply indebted to Dr. David Shar|i and to Mr. F. Muir for a l)etter know- 

 ledge and undei-standing of the anatomical arrangement of tlie parts of tiie male 

 genitalia. The eighth sternite shows no variation, — it is pai-tially chitinised in 

 the fonn of a pair of roughly triangular pieces which do not quite meet in the 

 median line. In a private letter Dr. Sharp states that the last ventral segment 

 (i-c-, the eighth) in Acaiitholophus is in the condition normal for Rhyncophorn. 



Kelatioti to Other (li'tiera. — AcattUioUiphus is related on tlie one hand to 

 Cubicorrlii/nchiis, and on the other to Iliiborrln/nchits. The point of distinction 

 between Acantholophus and Cubicorrhynchus is not altogether easy to make; tlie 

 character on which T rely to separate the two genera is the upper rostral surface. 

 In Acanlholoplnis tliis is always to some extent excavate, and never presents 

 the broad Ihil appearance so characteristic of Ciibicorrln/ncliiu^. For this reason 

 T place ('. ma.rimiift in AvatithiiJoplius. as it has a dee|)ly excavate i-ostrum, 

 tliougli in general its facies resembles that of Cuhicorrhi/nchns; it is, however, 

 certainly congeneric with A. grmudaluts Sloane and ,1. blackburni Ferg. (= A. 

 simplex Blackb. ) which their authors placed unhesitatingly in Acantholophus. 

 The species of (Cubicorrhynchus are for the most part smaller than those of 

 Acanthi)lnplius. and with few excc-ptions do not possess elytral tul)ercles. The 

 species here grouped together under section IT. possess many features in common 

 with Ciibicnrrhyvchus and at variance with the other section of Acantholo})hus, 

 which, however, they resemble in their general facies. Probably this section will 

 eventually be constituted a separate genus. 



