1922] Brolemann: Female Par aiidids 291 



gently sloping outwardly. An abbreviated sulcus is seen on each side 

 of the wall, running close to, and parallel with the anterior truncation, 

 which is rather broad. The apodema {a) does not exceed the second 

 third of the ridge; it is deeper in the middle than at both ends and 

 sends forth a median, club-shaped, and an apical, strangely hooked 

 diverticulum {d. Fig. 15, 18). The operculum (O) is a quite unimportant 

 plate,_ the form of which is not even definite, as in one of the specimens 

 examined it was scarcely chitinised, while in another no trace of chitinisa- 

 tion could be observed, the operculum being represented by a soft 

 membranous fold. 



Immature Female. — In an immature female (Fig. 19, 21), the sternal 

 plate of the second pair of legs is three times broader than long in the 

 middle, slightly arched, with the median angle scarcely produced. 

 The immature vulvas {W, Fig. 19) sit on a membrane stretched behind 

 the second pair of limbs, on a level with the laterally reflexed ends of 

 the sternite. Each vulva is formed of three rounded swellings disposed 

 diagonally, the anterior-outer swelling (0, Fig. 21) being the operculum, 

 the anterior-inner {iv) representing the inner half of the mound, and 

 the posterior {ov) the outer half. A rudimentary conic apodema {a) 

 is to be observed between the two last mentioned swellings. 



It is well worth insisting upon the features of the vulvae of 

 P. tiganus, as not only the condition of the operculum is decid- 

 edly exceptional, having never been met with before, but the 

 aspect of the whole organ is so different from what will be 

 found in the following species, that the relationship between 

 the latter and tiganus appear very distant, as far as vulvae are 

 concerned. 



Paraiulus pennsylvanicus (Brandt, 1840), Wood, 1865. 

 (Fig. 22-27). 



9. Length 39 mm.; diameter 2.25 mm.; 64 segments, of which 2 apodous; 

 118 pairs of legs. — Adult. 



9. Length 34 mm.; diameter 2.15 mm.; GO segments, of which 2 apodous; 

 110 pairs of legs. — Adult. 



Interocular sulcus moderately impressed. Mandibular cardo (Fig. 

 24), shorter than in P. tiganus, about two-fifths of the length of the 

 stipe. Breadth of the stipe equal to two-thirds of its length; anterior 

 and ventral edges unite in an evenly curved line without any trace 

 of an anterior angle. The promentum thins out apically, the lamina 

 linguales being almost in contact; the latter bear a row of three to four 

 short setae and two premarginal long bristles. 



Anterior body segments almost cylindrical, the diameter of the 

 second segment is only a little larger than that of the head (Fig. 22, 23). 

 Profile of the second segment rounded; ventral ridges raised; dimples 

 more or less angular and subquadrate' (Fig. 2b, A); ventral lobes broad, 

 encroaching on each other. The third segment is not shortened 



