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cuticular striae. Many of these zooecia are practically empty of cellular contents except for one 

 or two brown bodies: but in sonie of them a young polypide-bud can be seen close to the 

 basal end of the zooecium. It may thus be inferred that in a certain proportion of cases the 

 polypide is reconstituted in zooecia which have undergone histolysis. 



The structure of zooecia with functional polypides is shown in fig. 16. The quadrangular 

 orifice leads into a vestibule which is of great length, as it is about half the length of the 

 zooecium. The lophophore lies near the basal end of the zooecium during retraction, and the 

 tentacles are bent at their tips. Their number (8) could be ascertained with certainty from one 

 or two polypides which had died with their tentacles protruded. The pharynx is large and lies 

 in the prolongation of the line of the bundie of tentacles. The oesophagus commences close to 

 the proximal end of the zooecium and runs distally. It is of considerable length and it opens 

 into the stomach without forming a gizzard. The parietal muscles consist of a doublé series of 

 sharply defined bundies, each of two or three strong fibres. 



The zooecia contain a number of minute, sharply defined spherical vesicles, varying in 

 diameter from 3.5 to 1 1 [j.. These structures appear to be of the same nature as the "excretory 

 vesicles" which I have described in certain Cheilostomata l ) and Cyclostomata 3 ). 



The following measurements, in y., will give an idea of the size of the zooecia and other 

 parts: — length of zooecium with retracted polypide, 700 — 850 ; diameter, 200 ; length of 

 vestibule or everted kamptoderm, 350 — 400; of collar, 210; diameter of stolon, 40 — 50. 



Fam. Mimosellidae Hincks. 



Mimosellidae Hincks, 1877, "On Brit. Pol.", II, Ann. Mag. Nat. Hist. (4) XX, p. 532. 

 Mimosellidae Hincks, 1880, "Hist. Brit. Mar. Pol.", p. 555. 



This Family, which contains the single genus Mimosella, is distinguished by possessing 

 a pair of muscles by which the main part of the zooecium is moveable on its narrow stalkdike 

 proximal portion. 



Mimosella 3 ) Hincks. 



Mimosella Hincks, 185 1, "Notes Brit. Zooph.", Ann. Mag. Nat. Hist. (2) VIII, p. 359. 

 Mimosella Hincks, 1880, 1. cit. 



Mimosella Waters, 1910, "Rep. Mar. Biol. Sud. Red Sea", "Bry. II", J. Linn. Soc. Zool., 

 XXXI, p. 241. 



Zoarium erect or repent. Zooecia deciduous, narrow proximally, in which region there 



are paired muscles by means of which the zooecium can be moved on its stalk. Tentacles 8. 



Gizzard wanting 4 ). 



1) Harmer, S. F., 1891, "Excr. Processes Mar. Pol."', Q. J. Mier. Sci., XXXIII. p. 129. 



2) Ibid., 1898, "Dev. Tubulipora\ Q. J. Mier. Sci., XLI, p. 113. 



3) Mr E. O. ULRICH has suggested that l'inclla. a supposed Lower Silurian Ctenostomatous Polyzoon, is related to Vesicularia 

 and probably to Mimosella (1890, "New Lower Silurian Bry.", J. Cincinnati Soc. Nat. Hist. XII, p. 173). See also Clrich and Bassler, 

 1904, "Rev. Pal. Bry.", I, "Ctenostomata", Smithson. Misc. Coll. (Quarterly issue) XLV, pp. 256 et seq. 



4) Vigelius, W. J., (1887, "Zur Morph. d. mar. Bry.", Zool. Anzeiger, X, p. 239) states that a gizzard is present in M. gracilis\ 

 but Waters (t. cit., p. 246) denies the existence of this structure in Mimosella. 



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