6 Pol. 
POLYZOA. 
nacula ” are true buds with embryos, having both endoderm and ecto- 
derm, and corresponding to the statoblasts of Fredericella. This last is 
regarded as a transitional form. Further modification takes place either 
by alteration in the chitinous cyst or multiplication of the tentacles. 
The lophophore becomes more developed ; statoblasts appear both with 
and without swimming ring ; the sessile ones disappear, replaced by 
spinose anchor-bearing forms. 
As regards Ontogeny , the spermatozoa originate in spermatides of the 
endoderm, the head corresponding to the nucleus, and a “ residual body” 
being present. The ova have a similar origin, and are surrounded by 
epithelial cells, constituting a simple ovary. Fertilisation occurs within 
theovary. Segmentation is complete; part of the ovum forms a maternal 
envelope and degenerates. The gastrula is embolic, and its cavity is 
the future coelom. Invagination takes place at the anterior pole, the 
ectoderm lining the alimentary canal and the ganglion being formed from 
it. There are three invaginations into the polypide, the two lateral from 
the lophophore, the median part of the mesenteron. The hypoblast of 
the gastrula is regarded as mesoderm, and the Polyzoa as a link between 
the Ccelenterata and the Enter ccelia. Nitsche’s accouut of the develop- 
ment of statoblasts is confirmed ; KrAepelin. 
The ectoderm never disappears in the Polyzoa , as asserted by Yigclius, 
as may be shown by staining with silver; Ostuooumoff (1). 
For a discussion of the systematic valuo of tho zoariutn and zcoecium, 
see Koschinsky, pp. G— 15. 
GEOGRAPHICAL DISTRIBUTION. 
Kara Sea. 51 species (2 new); Levinsen. 
Jan Mayen. 76 species ; Lorenz. 
Livonia. 5 freshwater species ; Schmjdt. 
Irish Coast. 14 species recorded by Nichols. 
Liverpool Bay and District. 98 species (66 Cheilostomata, 13 
Cyclostomata , 17 Ctenostomata , 2 Entoprocta ,) recorded, with notes by 
Lomas. 
Channel Is. 20 species recorded by Kcehler, p. 58. 
Montecchio Maggiore. 105 species (6 new) ; Gottardi. 
Bohemia. 13 species (2 new) enumerated, with notes and descriptions 
by Kafka. 
South Bavaria, 'll species (42 new species, 6 new genera) from Ter- 
tiary formations ; Koschinsky. 
Gulf of Sebastopol. 11 species ; Ostrooumoff (4). 
North A tlantic. 7 species ; Busk, p. iv. 
South A tlantic. 22 species ; id. t. c. p. v. 
Southern Ocean. 11 species; id. t. c. pp. v & vi. 
Australian Region. 17 species ; id. t. c. pp. vi & vii. 
Philippine Is. Crisia denticulata, Lmk. , n. var. gracilis ; id. t. c. 
p. vii. 
Honolulu. Idmonea radians , Link. ; id. t. c. p. vii. 
