1922] Brolemann: Female Paraiiilids 293 



narrow, shorter than the lamina? linguales, the inner angles of which 

 are almost in contact. Each lamina bears two setae and two pre- 

 marginal bristles. 



Anterior segments not obviously swollen (Figs. 2S, 29). Ventral 

 region of second and third segments produced far beyond the coUum. 

 Second segment with posterior margin raised and abruptly excised, 

 and with short, triangular ventral lobes. Ventral ridge strong, almost 

 angularly bent; the dimples are broader than long and stretched 

 diagonally (Fig. 31, .4). The third segment is not narrowed ventrally; 

 its pleural margins are excised, the posterior angles ending into short, 

 ventral lobes, the apex of which remain separated by a wide gap (Fig. 

 29). The anterior angles send forth rounded processes which are 

 connected by a chitinous bridge {P2), homologous with the sternite 

 of the second pair of legs. The sternal bridge shows traces of the 

 stigmata and of the tracheal stalks, the limbs being completely 

 atrophied. 



The sternal bridge, the pleural excision and the ventral lobes of 

 the second segment circumscribe an oval space through which the 

 summit of the vulvae is seen to protrude. Wood (1865, p. 200, Fig. 33) 

 has given a drawing of the vulvae of immaculatus , which gives a correct 

 idea of their general aspect. The vulvs stand side by side and cling 

 together, although no fusion seems to intervene (Fig. 32). The 

 operculum is a thick, subquadrangular plate, more than twice as high 

 as broad, with blunt angles; the bristles of the anterior surface are rare 

 and only to be found near the apical margin. On its posterior surface 

 a thickening is seen adjacent to the inner distal angle and projecting 

 above the ridge of the mound {H, Figs. 32, 33). The latter is extremely 

 asymmetrical. Seen in posterior aspect, the outer valve {ov) appears 

 as a triangular plate gradually narrowed proximally and truncate 

 distally, the distal margin being about half the length of the plate; 

 it leans inwardly so as to cover most of the posterior surface of the 

 organ. The inner valve {iv) is more like a subcylindrical pillar, much 

 lower than the outer valve ; yet its base being on a level with the center 

 of the outer valve, its summit considerably exceeds the apical truncation 

 of the latter and almost reaches the top of the operculum. No horse- 

 shoe plate is present, unless an apical thickening of the outer valve, 

 which connects it with the inner valve, be considered to be its homologue. 

 The ridge is hidden to view, being bent cephalad and dipping obliquely 

 towards the base of the organ (Fig. 34). The apodema is very short 

 and sends forth a comparatively small, pear-shaped diverticulum. 



The sternal plate of the third pair of legs has a special shape, different 

 from that of the other segments in having the anterior angles produced 

 laterally and the sides sinuous. 



It is noteworthy that, in immaculatus, conditions are similar 

 to those met with in tiganiis, in so far as the vulvar chamber has 

 a rigid aperture supplied by the third segment. However, the 

 comparison cannot be carried on any further as the vulvae 



