176 
The irish Naiuralist. August-September, 
and its single species transierred to Actaeonia under the name 
A. Cocksi. As Actaeonia (Ccnia) Cocksi was described and 
figured from a mature individual it seems best to adopt for 
the two species here fused into one the name A, Cocksi 
rather than the contemporaneous A. corrugata, founded, 
as I believe, on an immature specimen. 
In some of its earlier stages, while the head appendages 
are as yet imperfectly developed, Actaeonia is very similar 
in form and colour to Limapontia. The eggs and egg- 
clusters in the two genera are, however, strikingly dis- 
similar. In Actaeonia the clusters are rounded elliptical, 
while the eggs are some six times as large as those of Lima - 
pontia and much less numerous, an average of 13 being 
given by 23 clusters laid in captivity by Irish specimens. 
The bright orange yolk is immersed in a milky medium, 
so that the clusters appear as white spots about 2 mm. in 
diameter standing out far more conspicuously from the 
Cladophora twigs to which they are usually attached than 
do the elongated pellucid clusters of Limapontia. 
The specific character relied on by Alder and Hancock 
as distinguishing A . corrugata from A . Cocksi is the form of 
the head appendages. These are described as short, flat, 
whitish tentacular processes in the first species, and as 
linear cylindrical tentacles of moderate length in the second. 
A first examination of many living Dublin Actaeonias 
showed that they possessed the short, flat tentacular pro- 
cesses distinctive of A . corrugata ; but on a second examina- 
tion made from 3 to 6 weeks later these short flat processes 
were found to have developed into the linear and cylindrical 
tentacles of .4. Cocksi. One egg-cluster of 12 eggs taken 
at Bullock was successfully hatched out on the 19th March, 
1912, and the gradual development of the head appendages 
of the young animals was kept under observation for a 
period of seven weeks during which they passed through the 
form characteristic of A. corrugata into that distinctive 
of A. Cocksi.'^ 
At no time during the development of these eggs was 
any trace of shell or veliger stage observed. The young 
* For further details as to the behaviour of A. Cocksi in the early 
stages of its development after leaving the egg, sec Colgan '12. 
