278 MR. H. D. BAUCOCK ON 



M. turriformis is a very distinct species of the Plataleoides 

 group. 



M. cornuta is distinguished from all other species here 

 described by the excess of length of the second over the first 

 joint of the pedicel. 



The distinction between M. alhicmrata f»nd M. lateralis is not 

 very satisfactory, and one specimen occurs which suggests that 

 these are only varieties of a single species. 



The males M. ramosa and M. geclongensis are well marked, 

 but there is no information to suggest to which (if any) of the 

 females they belong. 



The chief diagnostic differences between the various species of 

 Myrmarachne are given in the key preceding the descriptions. 

 The group is a difficult one. In general shape the prosoma falls 

 into three classes, viz., somewhat squat with a narrow and shallow 

 thoracic groove and thorax falling rapidly behind it {maxillosa, 

 hiseratensis), caput towering high above thorax {turriformis), 

 and caput and thorax separated by a wide groove of moderate 

 depth with caput not much higher than thorax (all the rest). 

 The prosoma is further characterized by the presence or absence 

 of a wedge of white colour below the thoracic groove, but this is 

 liable to be almost oblitei^ated. 



Constriction of the opisthosoma or the absence of it seems a 

 constant character, though its depth and the extent of light 

 coloration about it are variable. The shape of the unguis and 

 armature of the falces in the male are always characteristic. 



The shape of the sternum, though in cases appearing very 

 definite, is certainly variable to a considerable extent and except 

 in extreme cases is a doubtful guide. The epigyne appears to 

 differ in the figures, but it is probably more due to differences in 

 condition than specific differences. The male organs all consist 

 of a fine coiled spine of about 1| turns with slight, if any, 

 specific differences ; but distinction may be based on the relative 

 lengths and shapes of the last three palpal joints and the terminal 

 process of the tibia, none of which, ho'wever, is particularly 

 striking. 



In both sexes the number of spines below the patella and tibia 

 afford marked distinctions and are probably as good a first guide 

 as anything. They are, however, liable to be rubbed ofi" and are 

 not absolutely constant. 



In every case the practice adopted has been to start with a 

 detailed description. This has been followed in the case of 

 Myrmarachne by a shoi't description or diagnosis. Finally a note 

 is given stating the place where and circumstances under which 

 specimens were taken, any particulars concerning them and any 

 measurements made. In the case of these last it must be 

 remembered that the specimens, having been in spirit for years, 

 Avere very brittle and difficult to measure with accuracy, and that 

 the figures given must only therefore be taken as approximate. 



