1922] Brolemann: Female Paraiulids 297 



the synoperculum is poorly chitinized, but lacks the furrow observed 

 in impressus. The apodematic gutter (a) is by one-third shorter 

 than the mound; it appears distorted by numerous, densely packed 

 loops and terminates caudad with a long, rod-like diverticulum, bent 

 at right angles near its base and clavately enlarged apically (d) . 



The sternite of the third pair of legs is unusually widened cephalad, 

 its breadth largely exceeding half the diameter of the segment (Fig. 

 45, B). 



Immature Female. — In a larva admitted to belong to the last stage, 

 the mandibular stipe is rounded in front, no trace of inferior angle 

 being obvious. The second segment has its ventral margins less pro- 

 duced. The third is quite different from the corresponding mature 

 segment, as it is gradually narrowed ventrally, the inner margins running 

 obliquely in the lobes, very much as in the second segment. The 

 second pair of limbs is unmodified, i. e., it shows the structure of the 

 ambulatory legs, except that the coxae are longer, as is the case with 

 larvae of other species. 



The immature vulvae (Fig. 50) remind of those of impressus, as 

 the opercula are low, transverse plates, with distal margin gently 

 arched, but not fused mesad. The mounds appear as half-moon- 

 shaped bodies, divided by a shallow depression, with a linear slit and 

 rudiments of the horse-shoe and of a digitiform diverticulum. 



Paraiulus ellipticus B oilman, 1887, 

 (Brolemann, 1896-1902).* (Figs. 51, 52). 



Gnathochilarium as in pennsylvanicus. The twisted ventral lobes 

 of the third segment are very prominent ventrad. A rough outline of 

 the anterior aspect of same and of one of the limbs of the second pair 

 has been published in 1902. Traces of the second sternite are preserved. 



Synoperculum very deeply split mesad (Fig. 51); on each side the 

 distal margin is slightly curved and sloping laterally, being in addition 

 strewn with tiny setae. Lateral margins sinuate, prominent at a short 

 distance from the base. Heart-shaped projection {H) somewhat as 

 in venustus, its edges being likewise expanded into flattened lobes, 

 but the latter remaining far apart from the outer margins of the syn- 

 operculum; the lobes converge abruptly, uniting in a ploughshare-like 

 process (x) bent cephalad and driven between the summit of the 

 mounds (M), the bases of which remain in contact. The valves of the 

 mound are very dissimilar, the outer (ov, Fig. 52) being somewhat 

 higher and appreciably shorter than the inner, causing the ridge to 

 face obliquely backwards and externally. The ridge (r) is wide and 

 divided by a conspicuous slit. The apodematic gutter is comparatively 

 short, dipping perpendicularly, provided with some rounded loops 

 and with a fairly long diverticulum, much as in venustus. 



* This specimen being no longer in the author's collection, the secondary- 

 structures had to be omitted. 



