1922] Brolemann: Female Paraiulids 295 



shorter than broad, their apex not overreaching the distal margin of 

 the synoperculum. The latter is interrupted mesad, the notch being 

 comparatively narrow and shallow. The heart-shaped projection 

 {H, Fig. 40) is slightly impressed longitudinally in connection with the 

 notch; its lateral edges are attenuate and unite proximally with a low, 

 flattened, perpendicular keel, dividing the basal excavations. 



The mound (Figs. 40, 41) is a globular, asymmetrical body, entirely 

 clad with the valves, which are fused with the horse-shoe plate and 

 only connected caudad by a narrow, not particularly chitinised bridge. 

 The inner valve is the longest; it is inflated caudad, its upper margin 

 being feebly lobed; cephalad is a low, sharpened, diagonal crest (c). 

 The outer valve is divided anteriorly by a wide perpendicular furrow 

 (w), the bottom of which is membranous, the valve being conspicuously 

 gibbous immediately backwards of the furrow. The upper margins 

 of the valves are pressed together, concealing the ridge. The 

 apodematic gutter (o. Fig. 41) is located in the anterior half of the 

 mound; it appears distorted by numerous loops and terminates in a 

 long and comparatively thick, gradually tapering diverticulimi. 



Ventral region of the fourth segment, as in Fig. 37, B. 



Immature Female. — In a larva of the last stage, the mandibular 

 stipe is gently narrowed anteriorly and rounded apically. The second 

 and third segments are neither swollen nor produced ventrad ; the third 

 is very different from what it is in adult and more approaches the 

 condition of the second segment, being even shorter than the latter. 

 The main points of the structure of the second pair of legs have already 

 been recorded. 



The immature vulvas (Fig. 42) are considerably more developed 

 than in the tiganus larva, being broader than the second stemite, 

 and several details being noticeable. The opercula have already 

 coalesced, their evenly arched upper margins uniting mesad and giving 

 rise to a wide angular notch; on each side of the notch the posterior 

 surface of the synoperculimi shows the raised area which, in the adult 

 organ, will be fused in a heart-shaped projection. The mounds are 

 broader than high and of comparatively much larger size than in the 

 adult; yetno other detail of their structure is obvious but a rudimentary 

 apodematic thickening. 



Paraiulus venustus Wood, 1864. 

 (Fig. 43-50). 



9. Length 33 mm.; diameter 2.45 mm.; 51 segments, of which 2 apodous; 



92 pairs of legs. — Adult. 



9- Length 33 mm.; diameter 2.42 mm.; 50 segments, of which 2 apodous; 

 90 pairs of legs. — Adult. 



9. Length 25 mm.; diameter 2.05 mm.; 51 segments, of which 2 apodous; 



93 pairs of legs. — Immature. 



