FORMICA. 323 



one carrying a fly-larva, the other a dead beetle (Silpha atrata), 

 return in a straight line from different directions to their nest 38 . 



On July 12th, 1913, having observed several rufibarbis workers 

 running about on a path near a sandy bank at Wey bridge, I en- 

 deavoured to find their nest, and commenced to pull up handfuls 

 of herbage on the top of the bank, which I let fall on the slope. 

 I then saw a worker approaching with a fly in its jaws and start to 

 mount the bank, and as the scattered herbage was directly in its 

 way, I feared the ant might be diverted from its nest, but when 

 it reached the obstacle, it never hesitated for a moment, but 

 running straight over it in a direct line, entered its nest on the 

 top of the bank, which I was thus enabled to find. 



Forel says the colonies of rufibarbis are sometimes small, but 

 usually of medium size, and none that I have found have been large ; 

 Wasmann, on the other hand, records large colonies at Luxemburg 

 consisting of over one thousand workers, and says they are generally 

 more populous than those of fusca zs . Schenck often found naked 

 pupae in rufibarbis nests at Nassau 12 , and I have had such pupae 

 produced in my observation nest from Weybridge. 



Forel 19 and Wasmann 38 record pseudogynes of rufibarbis, and 

 the former describes a mixed gynandromorphous specimen which he 

 captured on the wing, flying with normal males and females at the 

 summit of Monte Salvatore on July 1st, 1891 : 



Halves of head identical, but of such a character that it is impossible to 

 say whether they are male or female ; in form the head is exactly intermediate 

 between the two sexes. Both antennae 13-jointed as in the male, but scapes 

 too long in proportion to funiculi for this sex. Mandibles indistinctly denti- 

 culate, parti-coloured reddish black and brown, intermediate between male 

 and female, as are also the size and conformation of the eyes and ocelli. 

 Whole head more robust than that of the male, smaller than that of the 

 female ; black (hence male). Thorax indeterminate ; right half of epinotum 

 yellowish red, left half black, whereas the right half of the scutellum and 

 petiole is black, the left half reddish yellow ; hence the epinotum is female 

 on the right, male on the left side ; whereas the scutellum and petiole are 

 male on the right and female on the left. The three pairs of legs are sym- 

 metrical, yellowish, and have rather the form of the female. The wings, 

 being the same in both sexes, are indeterminate in the gynandromorph. 

 Gaster apparently female, globular, very small, with five segments, excluding 

 the petiole. Anus round, encircled by hairs as in the female, but it opens 

 above into a transverse, eciliate slit, situated between the hypopygium and 

 pygidium as if forming a second anus. The anus proper is cut into the 

 hypopygium. 20 



On July 29th, 1913, I captured a curious individual, which was 

 running rapidly among the workers in a nest of rufibarbis at Wey- 

 bridge, and which I at first took to be a pterergate, as it had the 

 general appearance of a large worker with wing stumps, but 

 when set and studied more carefully it appears to be an ergatan- 

 dromorphous specimen which may be described as follows : 



Head shape and size of large , black except mandibles and cheeks 

 anteriorly, which are reddish yellow ; median ocellus large, <$ ; lateral ocelli 



