148 [July' 



beyond the apex of the abdomen to nearly half the length of the first 

 segment. In fact, there are at least fourteen species of Pezomachus 

 in which the aculeus does not attain to half the length of that seg- 

 ment, and this feature cannot be safely relied upon even for the 

 separation of species, although Foerster uses it freely in his analytical 

 table. 



Both the transverse ridge and the tubercles on the first segment 

 appear to vary in different individuals of the same species, not, 

 perhaps, to any great extent, and yet suiBciently to cause confusion 

 when the identification is made to depend mainly upon them. 



Colour is a notoriously bad guide to species in this family, and 

 yet there appear to be certain well defined limits of variation. Here, 

 as in the Coleopterous genus Aphodius, there seems to be a tendency 

 among most of the normally black species to develop red in some 

 parts, and for this colour to vary greatly in extent where normally 

 present. In Fez. intermecUus, for example, the thorax and the first 

 abdominal segment range from entirely black to entirely red, the 

 normal type being apparently that in which each has the base black and 

 the apex red. Where the abdomen is red-yellow and black, the extent 

 of each colour is subject to considerable variation, the second and 

 third segments being most commonly affected. Even where, as in 

 Fez. zonatus and fasciatus, the abdomen remains red, with a black 

 band, or bands, always on the same segments, these bands may cover 

 the whole segment, or be reduced to thin lines. On the legs the most 

 common variation consists of an increased amount of brownish tint, 

 especially on the femora and tibia?. The colour of the head appears 

 to be nearly constant, only varying slightly in the amount of red, 

 where this colour occurs in conjunction with black. 



Of all the organs the antennae seem to me to be least subject 

 to colour variation. The scheme of colour on these organs may be 

 divided into four main groups, namely: — Ist, unicolorous red or red- 

 yellow, varying only iu the intensity of the colour, and possibly in the 

 apex being more or less distinctly darker ; 2nd, unicolorous black, in 

 which I find no variety ; 3rd, having the base red and the apex brown 

 or black-brown — in this group the intensity of the colour, the extent 

 of the red base, and the more or less abrupt transition from one colour 

 to the other might form good sub-divisions ; and 4th, black or black- 

 brown, with the apex of the 2nd and the base of the 3rd red or 

 red-yellow. As far as my observations on Fezomichus, Fst., extend, 

 I have found no case of variation in the antenna} among individuals of 

 the same species, except in the intensity of the colour ; though Mr. 



