2o0 



of the zocrciiim. They altaiii Ihi'ir i^rcalcsl extent on the basal siirfacc, on which 

 they are .se])araled partly by a ralher liroad longitudinal hell, which is some- 

 what concave towards the centre and hirnrcatetl in Ihe Ijizooecial joint, j)artly 

 by the l)elt-shaped or ridge-liUe hileral branches, likewise concave and springing 

 from the just-menlioned belt. The supra-scapular chamber reaches some way 

 down the basal surface, luit a still larger part of it can be seen on the frontal 

 surface, where the two chambers are separated by a narrow ridge passing tlown 

 to the incision between the two umbellate processes of the aperture, the free 

 edges of which form ])art of the boundary of the two chambers. From the proxi- 

 mal end of each undiel the boundary ridge runs in a straight line towards the 

 avicularium and then bends in an arch-shaped ridge, the distal ])art of whicli is 

 parallel with the margin of Ihe frontal area of the avicularium. The infra- 

 scapular chambers, which are the largest, form the greater \)m[ of the basal 

 surface of the zott'cium and a large part of its lateral surfaces, and each cham- 

 l)er is separated from the large, rounded quadrangular pedal chamber (fig. a b) 

 by a ridge springing from the proximal end of the basal wall, which first passes 

 obliquely distally and after another bending joins the sternal area. In the l)i- 

 zoa?cial internode the greater part of the distal surface is occujjied by a large 

 mendiranous chamber, whicli sends a triangular jiortion down the frontal as well 

 as the Jiasal surface. This chamber is bounded on either side liy a low ridge, 

 which runs from the ring of the joint lo Ihe incision in the biloliate marginal 

 expansion of the aperture (hg. ae). A thick but rather short horizontal ridge, 

 situated immediately on the distal side of the intermediate space between the two 

 apertures (fig. 5 e), incompletely divides the cliamber into two parts, viz. a smaller 

 frontal one and a larger distal and basal. Each of these communicates with the 

 daughter-zoo'cium through a small rosette-plate with 2 — 3 pores, and Ihe entire 

 chamber must be regarded as Ihe adzooecial, supra-scapular chamber of the 

 molher-zoa'cium. The adzoo-cial infra-scapular chamber of the mother-zoo'ciuni 

 is wanting, and with regard lo Ihe other chambers in the bizod'cial joint refer- 

 ence may be made to the explanation of the plates. 



The ocecium. The gonozooecium, which is only about half as high as the 

 covering kenozoo'cium, is situated sometimes on a mothcr-zoo'ciiini, sonietinies 

 on an inserted single zooecium. The sternal area, which is a little smaller than 

 the aperture, is provided with 5 elongated feheslrae somewhat pointed at the di.s- 

 lal end, which increase in length towards the centre but all reach nearly right 

 up to the proximal margin of the aperture. Inside this row of openings, which 

 reminds one of a visor, a very broad, rounded cryptocyst lamina is seen. On the 

 other hand a frontal sinus and ribs or spines are complelelv wanting. The 



