BY R. J. TILLYARD. 333^ 



■which the ovipositor has completely disappeared, leaving the 

 ninth segment hollow without any prominent covering from the 

 underside of S. 



It thus appears that the female sex-organs are, in this group, 

 too variable to be of much use in generic separation. The group 

 of four species last-mentioned is the only one in which I propose 

 to use it as a generic character. 



Male Sex-Organs. — Throughout the group the primary sex- 

 organs of segment 2 are not prominent, the sheaths being fairly 

 large and well-rounded and forming an effective protection to the 

 penis, which is deeply recessed between and below them(see Plate 

 vii., fig.1.5). The foi'm of the penis itself is probably only of 

 specific value, varying, no doubt, considerably with the variation 

 already described in the female sex-organs. In any case, as the 

 specimen has to be saci'ificed in order to examine it, it is inad- 

 visable to use it in classification. However, I have figured the 

 penis of three species typical of the three genera into which I 

 propose to subdivide the group. The general shape is somewhat 

 the same in all three; but in S. ev,stalacta{fig.24:) there is a long 

 curved filament projecting from the base, followed by a row of 

 hairs decreasing in size; in S. gutiata(^&g.25) this filament is 

 absent, and the hairs are more numerous, but shorter; in S.fiavo- 

 ^e?'mi?i«^a(fig.26) the filament is absent, and the hairs few. On 

 the upper part, S. euslalacta possesses a long curved filament 

 similar to that on the base; S. guttata a shorter one, nearly 

 straight; and S. Jiavoterminata the merest rudiment of one. I 

 have been unable to spare specimens from the rarer species to 

 carry this investigation further; nor do I think it of much \ alue 

 towards forming a really usefxd classification of the group. 



We now turn our attention to the secondary male sex-organs, 

 i.e., the anal appendages of the abdomen, used as claspers in 

 holding the female. These are figured for every species (except 

 S. miranda, of which the male is unknown) in Plate vii., figs. 1-1 4. 

 We find here three distinct groups, each of which is associated 

 with a corresponding form of the abdomen. In the first group 

 (figs. 1 to 8), the superior appendages are long, and more or less 

 wavy; the corresponding abdomen is pinched at segment 3 or 4, 



