215 



tlie genus Clauijxnclld the inoxiinal one is also icprcsenk'd by a single rosette- 

 plalc. While the proximal group serves as a conimunicalion with the pedal 

 chanihcr llic distal group serves either as conimunicalion with the sca[)ular 

 chamber only as in Sciilirclla plfifiioslonid, Sr. inlcrinedid, Sr. venlricosa, Cal. 

 niiir(/(iriltii('ii, or as conimunicaliDn with Ihe inlVa-scaiiular ciiambei' as well, e. g. 

 Sc. (implwra, Sc. laiira, Sc. Wilsoiii and the species ol' the genus (Idli-narid. If the 

 scapular chamber is developed into ;in avicularium, its rool' or distal wall (Pi. XI. 

 figs. 1 c, 3 b, ;j e, 4 b) is luiiiished with a number ol' rosette-plates forming a 

 communication with the supra-scapular chamber, while the proximal wall fur- 

 nished in the same way (IM. XI, figs. 1 e, 2 b, .'{ a, 7 b) makes a se|)tum for the 

 infra-scapular cluMuber, which, as slated above, in a series of species may also 

 be in direct communication with the zoo'cium. If on the other hand the scapular 

 chamber has not attained this degree of (levelo|)inenl it will coalesce with or be 

 only incompletely separated from the adjacent chambers. While as a rule there 

 will be no difficulty in distinguishing the various lateral chambers belonging to 

 the solilaiy zoci'cia oi' those belonging to the outer (abzocccial) sides of the bi- 

 zoo'cial ailiculale parts, il may be more diflicult to identify several of the lateral 

 chambers belonging to the inner (adzocecial) sides of the two zoo'cia in a bi- 

 zooecial segment. Moreover these two zoa-cia are not of etpial value, as we must 

 distinguish between a motlier-zoo'cium springing fiom the pioxiinaily situated 

 segment, and a daughter-zou-cium without communication w'ith the segment but 

 issuing from the mother-zod-cium. 



If Ihe adzoa'cial side of the daughter-zooecium is furnished with an avicula- 

 rium, its three distal lateral spaces will always be clearly developed, e. g. in 

 Costicella Imstata (IM. XX, fig. Mb), Ptcmcella alula (PI. XXI, fig. 4a;, Calenaria 

 elefjans (PI. XXI, fig. 2 a) and (>//. j'oriiiosa (PI. XXI, fig. 3 a), whereas its j)edal 

 lateral chamber (d. IV; is usually wanting. It is however pre.seiil in all the spec- 

 ies of the genera Coslicrlhi and (Mlenaria, in Slrojihijiord lldivnji as well as in 

 Sciilicelld sdcciildld, Husk and .Sc. /'/•(V/iV/ri, Waters' which two species may be 

 regarded as transitional forms between the genera Sculicella and (jiteiidria. Al- 

 though the daughter-zooecium itself has lateral chambers it still takes the 

 same place in relalion to the mollur-zoo'cium as the scapular eliambcr in a 

 solitary zoa-cium, being in communication with the mother-zoo'cium through the 

 group of rosette-plates described above as the distal, and the adzoiecial, distal 

 lateral chamber of the mother- zotrcium which communicates with the daughter- 

 zooecium through a group of rosette-plates, must accordingly be explained as the 



' 115, pi 1, fig 1 a. 



