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adzofrcial, supra-scnpiilar (m. I) laU-ral clianiber of the molher-zoa>ciiini. This is 

 clearly seen e. g. in Scnticclla iiidciiUild (PI. XX, fig. 5 b), in which species Ihis 

 chamber lies opposite the corresponding abzoa-cial, supra-scapnlar lateral chamber, 

 from which il is only sej)arated by a short raised line. Although the daughter- 

 zo(rcium, as said before, may be considered the adzooecial, scapnlar chamber of 

 the mother-zod'cium, and we cannot for this reason expect to find an avicularium 

 on the adzon^cial side of the mother-zooecium, the species of the genus Pterovdla 

 (PI. XXI, fig. 4 a) make an exception lo the rule, a small adzooecial avicularium 

 being always jiresent. The adzooecial, pedal chamber of Ihe mother-zoo-ciuni 

 (m. IV), whicii is always developed, is not difficult to find, and il then only 

 remains to determine the adzotrcial, infra-scapular chamber of tiie molher-zofi'- 

 cium (m. III). We have seen that an infra-scapular chamber is only independently 

 developed in such zoo-cia as are furnished with an avicularium wilh which they 

 communicate through the proximal wall of the latter, but that in a series of s[)e- 

 cies it also communicates wilh the zoo-cium itself through some of the rosette- 

 plates in the distal grouj). In accordance wilh our conception of the daughter- 

 zooecium as being the scapular chamber of Ihe molher-zoa-cium, we must consider 

 the only lateral chamber that we have not yet explained as the adzoa^cial, infra- 

 scapular chamber of the mother-zotrcium. It is in most cases a very small, oval 

 or pear-shaped, sometimes almost slit-like space, situated almost in the middle 

 of the boundary line between Ihe two zoo'cia of the segment, and rarely allain- 

 ing any considerable size. Its extent is largest in Strophiiuini lldrrfiji (PI. XXI, 

 fig. (i a), in which besides extending a little into the dnugbler-zott'cium il also 

 occuj)ies half Ihe frontal surface of the molher-zoa-cium. In Sciilicclla Wilsoni it 

 also attains a considerable size, filling as il does the greater part of the deep 

 dej)ression between the sternal areas of the molher-zocEcium and the daughler- 

 zooecium. In the species of the genus CdleiKtria this boundary chamber has like 

 the ordinary infrascapular chamber a doui)le inner communication (through ro- 

 sette-plates), viz. both with the daughter-zou'cium and with the molher-zoa>cium, 

 while the corresponding chamber in Sciiticella species only communicates with 

 Ihe mother-zoopcium. A similar dilTerence, as already mentioned, is found within 

 the genus Scdticella, all Ihe roselle-plates of the distal group serving in .some 

 species as a communication wilh the scapular chamber, while in others some of 

 them form a communication wilh Ihe infrascapular one. ^^'itll respect lo Ihe 

 above chamber we must still notice that il generally occurs somewhat incon- 

 stantly within the genus, in Scuticelht mdrtjdrildcea for instance it is absent, while 

 it is present in the form described in Ihis work under the name of <SV. mar- 

 (jaritaced, var. connedens (PI. XX, fig. 3 b), but which perhaps ought to be con- 



