REPORT ON THE POLYZOA. 27 



In the suboral aTicularian chamber, near to the mandibular end, there are two 

 curious bodies partly embracing the muscular bands. The lower and wider one appears 

 at first sight thin, as if it were a membranous wall separating the chamber, but sections 

 leave no doubt in my mind of its being a sac, and the walls are formed of small 

 nucleated cells. The smaller body rests upon this, and near the centre is tubular, 

 spreading out at each end into a small gland-like body. In dissections or sections these 

 two bodies usually adhere together and come away with the muscles. 



Above there is a mass of " endorsac," which often assumes an annular form, and 

 threads spread out in all directions, in some cases seeming to be attached to the larger 

 of these sacs. The presence of this mass of endorsac is usual in the avicularia of the 

 Chilostomata, but its taking an annular form seems to have been unnoticed.' 



As to the function of the other two bodies the problem seems a puzzle, but I do not 

 think that they must be considered alone, for in the zooecia of many species there is at 

 each side of the aperture a sac-like body, which in Retepora cellulosa (PI. III. figs. 12, 13) 

 attains a considerable -size, and it also occurs in Retepora tubulata, Retepora denticulata, 

 Retepora jacksoniensis, Retepora producta, Rhynchopora bispinosa, and I also found a 

 similar, but much smaller, body in the zooecia of Lepralia margaritifera, and they can be 

 seen in Cellepora coronopus. Ostroumoff ^ figures sacs similar to those of Retepora 

 cellulosa in Lepralia pallasiana, calling them glands, and Haddon figures two bodies 

 in Flustfa carbasea,^ but no description is given ; as Professor Haddon is on the 

 other side of the world, no answer can be received to my question for some time. In 

 this last case the bodies (I.e.) are not sac-like, but may nevertheless be homologous, as 

 in Cellepora pertusa from the Red Sea there are in a similar position two narrow tubular 

 vermiform bodies (PI. III. fig. 14). Unfortunately, the spirit has evaporated from this 

 specimen, which was bottled some years ago for further study. 



Whether these bodies are in any way to be associated with the organs described by 

 the late Dr. Joliet * as segmentary organs, is a question not unnaturally suggesting itself 

 The nature of these organs of Johet is left by his paper and figures somewhat doubtful, 

 but I do not follow him in his comparisons with the intertentacular organ of Farre, 

 Hincks, and Smitt. 



JuUien, who seems to have had good material available, only gives very large figures 

 of the polypide without any detail, and these do not differ from the generality of Chilo- 

 stomatous polypides. He does not, however, show either of the structures now described. 



■ It has always seemed to me that we must look for the explanation of the function of the avicularium to this 

 mass of parenchym, or endorsac, for the avicularia remain in activity when the polypides have all disappeared, and in 

 this way the tissues of the colony are indirectly in communication with the surrounding water, so that oxygenation 

 takes place, and the colony is kept alive. 



2 Ostroumoff, Archives Slaves de Biologie, torn, i., pi. i. fig. 17. I can at the moment refer only to the plate in 

 the Russian copy. 



3 Budding in Polyzoa, Micr. Journ., voL xxiii. p. 516, pi. ixxviii. fig. 12, I.e. 



* Orgaue Segmentaire des Bryozoaires endoprocte, Archivei de Zool. exTp&., tom. viii. pp. 497-512, pi. xxxix. 



