2 Pol. 
POLYZOA. 
15. Ruddy, T. List of Caradoc and Bala Fossils found in the Neigh¬ 
bourhood of Bala, &c. ( Polyzoa ). P. Chest. Soc. i. pt. iii. pp. 113-124. 
16. Shrubsole, G. W. Note on Glauconome disticha -from the Bala 
Beds of Glyn Ceinog. T. c. pp. 98-100. 
17. ^Vigelius, W. J. Die Bryozoen gesammelt wahrend der dritter 
und vierter Polarfahrt des ‘ Willem Barents’ in der Jahren 1880 
und 1881. Bijdr. Dierk. xi, 104 pp., 8 pis.; abstr., J. R. Micr. Soc. 
(2) v. p. 439. 
18. Vine, G. R. Polyzoa found in the Boring at Richmond, Surrey. 
Q. J. Geol. Soc. xl. pp. 784-794. 
19. -. Carboniferous Polyzoa of Northumberland. Naturalist, 1885, 
pp. 61-66, 208, 209, & 314-318. 
20. -. Notes on some Cretaceous Lichenoporiclce. Q. J. Geol. Soc. 
xl. pp. 850-854. 
21. -. Notes on Species of Phyllopora and Thamniscus from Lower 
Silurian Rocks, near Welshpool. Op. cit. xli. pp. 108-113. 
22. Waters, A. W. Fossil Cyclostomatous Bryozoa from Australia. 
Q. J. Geol. Soc. xl. pp. 674-696, pis. xxx. & xxxi. 
23. -. Cheilostomatous Bryozoa from Aiding and River Murray 
Clifts, S. Australia. Op. cit xli. pp. 279-306, pi. vii. 
24. -. On the use of the Avicularian Mandible in the determination 
of the Cheilostomatous Bryozoa. J. R. Micr. Soc. (2) v. pp. 
774-779, pi. xiv. 
GENERAL MORPHOLOGY. 
Writing of the mandibles of species of Polyzoa, Waters says, 
(24) p. 777, that “ certain processes in the mandibles of Cellepora and 
Adeona indicate differences in the muscular attachments, and that it is 
the muscular system, together with the opercula, which has the greatest 
classificatory value. 5 ’ 
Important points in the structure of the operculum in species 
of Membranipora are pointed out by Waters, (23) p. 282, and he says 
that “ it seems clearly advisable to include in one family only those 
forms in which the operculum is fixed in the flexible membrane covering 
the zooecial area (opesia, Jullien), as in M. angulosa and M. mem- 
branacea ; whereas those like Micropora uncifera, Busk, which have a 
complete operculum placed in a corresponding aperture with a calcareous 
border, should be placed in another.” 
Ostrooumoff (13) suggests that the calcareous skeleton is formed in the 
ectoderm either as a subskeletal layer ( Membranipora ), or as two layers, 
between which is the skeleton ( Lepralia ). This preliminary paper con¬ 
cludes with some observations upon the metamorphosis of the Bryozoa , 
illustrated by a diagram of “ Probryozoon.” 
The Polyzoa collected during the cruise of the ‘ Willem Barents 5 have 
been studied by Yigelius (17), and detailed particulars of the morphology 
