A REVISION OF THE GENUS LEPTOTHORAX. 91 



addition to numerous foreign examples that continental myrmecologists 

 have kindly lent me. 



The study of these ants presents considerable difficulty, owing to 

 the scarcity of specimens, particularly of (J s, and also the great 

 variation among the ^ s of some of the sub-species. In this 

 connection it may not be out of place to emphasize the great 

 importance, when collecting ants, of keeping the specimens from each 

 colony or nest separate ; a letter or number on the labels showing 

 this, is a great help, and, of course, whenever possible, all sexes 

 should be taken and labelled so as to show they come from the same 

 nests. Odd specimens, except in a few instances, are of very little 

 value. 



I have to thank my friend Mr. H. Donisthorpe for the use of his 

 data for the distribution of the species, for references and the loan of 

 specimens ; Dr. A. Forel and Prof. C. Emery, for descriptions and 

 ■drawings of specimens that I was unable to see ; and Messrs. J. 

 Bondroit (Belgium), and H. Scott (Cambridge Univ. Museum), for the 

 loan of specimens from their collections. 



Genus Leptothorax, Mayr. (Form, aiistr., 1855, p. 159.) 

 WORKERS. 



Table of $ s. 



L. Antennse 11-jointed L. acervorum, F. 



P Antennae 12-jointed .. .. .. .. .. .. .. .. ..1. 



1. Club no darkei- than rest of antenna . . . . . . . . . . . . 2. 



Club darker ,, ,, ,, .. .. .. .. .. ..3. 



2. A slight impressed line between mesonotum and metanotum. Spines 



long .. .. .. .. L. tuberum,F., suh-sp. nyla7ideri, Foerst. 



Without impressed line. Spines short . . . . . . sub-sp. corticalis, Sch. 



5. Thorax coarsely rugose. Spines very long and narrow. Club only slightly 



darker .. .. .. .. .. .. .. sub-sp. a/Zi/fix, Mayr. 



Thorax finely rugose. Spines shorter. Club nearly black. Top of head 



dark brown . . . . . . . . . . sub-sp. tuherum (s.str.), F. 



Like the preceding, but with longer curved spines and only front of head 



darker . . . . . . . . . . . . sub-sp. interruptus, Sch. 



Pahr ; a sharply defined dark band across base of first segment of gaster. 



I Club only slightly darker . . . . . . sub-sp. unifasciatus, Ltr. 



Antennte 11-jointed. Head and thorax rugose. An impressed hne between 

 the mesonotum and metanotum. Middle of clypeus almost always smooth, slightly 

 concave from the anterior to the posterior border. 

 Legs hairy. Spines of epinotum long, about two-thirds as long as the basal face 

 ■of epinotum. Red or reddish brown. Club of antennae, top of head and gaster, 

 and often middle of femora and a patch on the metanotum, darker brown. 

 L. 3-2-3*7mm. . . . L. acervorum {s.str.), Fabr. 

 Widely distributed and common. Colonies small, with one or 

 more que6ns, which are hardly larger than the workers. (Saunders^°, 

 in his remarks on the genus, states that "the 5 is small, scarcely 

 larger than the ^ " ; this only applies to acervoriDii, as the ? s of the 

 tiibeniiii group are not at all ergatoid in form, and much larger than 

 the g s.) The nests are usually situated in old stumps, roots, and 

 under bark, and often in stumps in the centre of nests of Formica 

 {liaptifurinica) aaiKjuinea, Fonnica rnfo, or F. exsecta, and the ants 

 seem to be unnoticed by the larger snecies. 

 7^' 



