ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
449 
Bryozoa. 
Synonymic Catalogue of Recent Marine Bryozoa.* — Miss E. C. 
Jelly is to be congratulated on the completion of this most valuable 
work. Though it is not to be expected that her fellow-workers will in 
all cases agree with her in her views of synonymous names, they are all 
greatly indebted to her for the long and patient labour necessary for a 
work of this kind ; in many cases a single species occupies more than a 
page, and sometimes nearly two. When a recent form is also known in 
the fossil state, references to the fossil specimens are given. Only a 
systematist will fully appreciate the service Miss Jelly has performed 
for students of the Marine Bryozoa. 
South Australian Polyzoa.f — Mr. P. H. MacGillivray in presenting 
a list of sixty-four species of South Australian Polyzoa, four of which are 
new, points out that the Australian seas are peculiarly rich in Polyzoa, 
more than 360 having been recorded from Victoria. Other parts of 
South Australia are, probably, equally rich. 
Arthropoda, 
Migration of Retinal Area in Arthropods.^ — Mr. G. Watase 
discusses the migration of the retinal area and its relation to the 
morphology of the simple ocelli and the compound eyes of Arthropods. 
He defines an ocellus as a visual organ in which the sensory nerve- 
end cells are segregated into definite groups called retinulae, a group of 
retinulae being again characterized by possessing a single dioptric 
apparatus in common. The author has already pointed out that a 
single retinula is morphologically a pit-like invagination of the skin. 
In his present paper Mr. Watase proposes to show how, granting the 
homology of the retinulae in both the compound and simple eyes, a 
group of such retinular invaginations becomes again invaginated as a 
whole. 
An area of primitive pit-organs which probably occupied the level of 
the general body- surface may migrate, under certain circumstances, 
inwards into the body in an embryonic stage. Since a slight difference 
in the level of a sense-area, in reference to the level of the surroundings, 
introduces a fundamental difference in the formation of the dioptric 
mechanism of an Arthropod, and, therefore, presumably a difference in 
functions, two organs serving different purposes may easily be formed 
out of the common type from a circumstance comparatively insignificant % 
at first. The composite mode of origin of the visual organ in 
Arthropods culminates in the remarkable phenomenon of migration of the 
sensory area of the eye first observed by Brookes and Bruce in the larva 
of Limulus. Strictly speaking, the early stage of the lateral eye of 
Limulus represents a structure which is neither a compound eye nor a 
simple eye, but the initial stage for both. The author does not look 
favourably on theories which derive the compound from the simple eye. 
Both types are considered to have been derived from a common source — 
a group of pit-organs arranged on the level of the surface of the body. 
* 8vo, London, 1889, 322 pp. 
t Trans., Proc. and Rep. Roy. Soc. South Australia, xii. (1889) pp. 24-31 (1 pi.). 
X John Hopkins Univ. Circ., ix. (1890) pp. 63-5 (2 figs.). 
