1889.] 377 



colony of ants. It is usually seen clinging to the under-side of the 

 stone when raised, with the hind body turned up over the back, and it 

 runs with great speed when disturbed. A fine Aleocliara (crassicornis ; 

 Lac.) has occurred, but very rarely, with this ant at Gibraltar and 

 Tangier, in early spring; and stray specimens of Coluocera formicaria, 

 Mots., and Thorictus gallicus, Peyr., are occasionally met with, the 

 latter looking, at the first glance, deceptively like a small Ster?wccelis. 



The large, powerful, and abundant ant, Aphcsnogaster barbara, L., 

 is the host of several very interesting species of Goleoptera, though I 

 have never found any Histeridce in its nests. The chief of these guests 

 is the minute and very anomalous Carabid, Pseudotrechus mutilatus, 

 Rosenh., which I first observed at Gibraltar in November, 1886. It is 

 a truly Myrmecophilous insect, being invariably associated with this 

 ant, except when found accidentally in flood rubbish ; its chief resort 

 being the sinuous galleries excavated by the ants in the soil beneath 

 the stones, though it is not rarely seen running actively on the under- 

 side of the stone itself. The Pseudotrechus seldom occurs singly, two 

 to three specimens usually occurring in one nest, but I do not remember 

 to have found more than half a dozen in a single colony. It is found 

 throughout the winter months, being, perhaps, most numerous in 

 February ; and is generally, though sparingly, distributed on the clay 

 soils near Tangier and Gibraltar, and I have also met with it at Esmir, 

 about twelve miles south of Ceuta, in Marocco. 



The singular little flat, oval, yellow Heteromeron, Oochrotus 

 unicolor, Luc. (which reminds one of a large Leptinus), is the most 

 common ant's-nest beetle throughout the district, and is entirely con- 

 fined to the nests of A. barbara, where it sometimes occurs in very 

 large numbers, especially when there is a quantity of loose debris, 

 husks of grass seeds, &c, in the galleries of the nest. "With it, also 

 frequently in some numbers, is found the little Coluocera formicaria, 

 Mots. ; also two species of the singular genus Merophysia, the smaller 

 of which (apparently undescribed) is restricted to the nests of this ant; 

 the larger one, M, carinulata, Hosenh., is found also with many species 

 of the smaller ants, always excepting the two species of Cremastog aster, 

 whose sickly and disagreeable odour (recalling that of butyric acid) 

 seems to be repulsive to insects of all sorts, and even to the woodlice 

 so frequently found in other ant's nests. Two species of Stajjhglinidce, 

 Kraatzia Icevicollis, Rey, and Homalota elongatula, Gr., occur somewhat 

 sparingly in the barbara nests, where also I have, on one or two 

 occasions, found Xantholinus longiventris, Heer, var., and the rare 

 Medon seminiger, Fairm. 



At Malaga, I have taken several specimens of a species of Oato- 

 pomorphus with A. barbara, and also found a single specimen of this 

 beetle on the summit of the Djebel Mousa (Ape's Hill), Marocco, at 



