A Monograph of the Formicidae of South Africa. 273 



occipital margin, and are also somewhat expanded outwardly, forming 

 the upper wall of a groove, the scrobe, which lies below them. This 

 groove is sometimes divided into two halves by a longitudinal carina, 

 the upper and lower halves receiving the folded scape and flagellum. 

 The scrobe in such a case is complete, and is usually distinguished 

 from the rest of the cheeks by its smoother and more shining surface- 

 It is particularly well developed in the sub-genera Triglyphothrix and 

 Xiphomyrmex. But in most species of Tetramorium (s. str.), only 

 the upper half of the scrobe, that which accommodates the scape, 

 is distinct, forming only a demi-scrobe ; or again, it may be defined 

 only in its anterior region, in which case it is referred to in the 

 following pages as a " trace of a scrobe." The sides of the declivity 

 of the epinotum are usually bounded by a raised margin, which 

 terminates below in two small teeth or lobes. These episternal teeth 

 are in most cases much smaller than the epinotal teeth above them. 



It should be observed that the 1st node of the petiole is inclined 

 at various angles, and that it is therefore impracticable to take 

 the measure of the length of the node through its thickness, as 

 unfortunately some authors appear to have done. In the following 

 pages, the length of the 1st node is measured from the anterior to 

 the posterior margin of the dorsal or posterior-dorsal face. It is 

 also necessary to define some of the terms used in these pages in 

 describing the sculpture of the chitin. 



In regard to such terms as "rugose," "rugulose," "striate," &c, 

 a certain looseness of definition exists, which is plainly apparent, if 

 the reader will compare half a dozen insects of different orders with 

 their original descriptions. The term " striate," for example, has 

 been used to express a form of sculpture consisting of raised lines, 

 as well as one which is made up, of incised lines or fine grooves. 

 Similarly, that which some authors describe as "coarsely striate" 

 has been termed " rugose " by others. It has therefore seemed 

 desirable to append a short glossary, defining the sense in which I 

 have used certain words. 



rugae (adj. rugose) = raised lines, usually rather coarse, which may 

 be more or less parallel over their whole length, but which 

 in part are also somewhat irregular, broken, wavy, sinute or 

 zigzagged. 



striae (adj. striate) = raised lines which are parallel, straight and 

 continuous. 



reticulate = a sculpture consisting of a network, the strands of 

 which are composed of raised lines. 



reticulate-rugose = a sculpture consisting of rugae, more or less 



