1904 - 5 .] Report on Medusae found in Firtli of Clyde. 
745 
and autumn. These come from hydroids which are constantly 
liberating medusae, and several generations occur during the year. 
A few species of the spring medusae are liberated from hydroids 
(Corymorpha, Hybocodon ) which have only one generation. 
These medusae are only present for about two months, and die off 
early in the summer, though at times a stray specimen may he 
seen in the autumn. 
Most of the medusae in our seas appear in the summer months — 
June, July and August. More species are found in July than in 
any other month of the year. In October medusae begin to die off, 
and practically disappear by the end of [November. 
The Tables I. and II. have been specially arranged to show the 
seasonal changes in the medusoid fauna of the Clyde. 
At Valencia, where the sea is a little warmer during the winter 
than in the Clyde, the medusae appear earlier in the year, and 
several species are present for a longer period. For instance, Lar 
sabellarum first appears in the Clyde in July, whereas at Valencia 
it appears in March, or even earlier. 
Limit of the Area for the Investigations of 1902. 
It was obvious to me, after the experience gained in 1901, that 
to include all the localities visited by the Laboratory steamer 
would only lead to confusion, as it would be necessary to take into 
consideration the physical conditions of those localities. 
As most of the tow-netting would have to be done close to the 
Laboratory and from a rowing boat, I fixed the limits so as to include 
all the tidal waters which flow past the two islands of Cumbrae. 
The northern boundary extended from Largs westward, across 
the northern end of Great Cumbrae, to Mount Stuart on Bute. 
The southern boundary extended from Portincross Castle to 
Gull Point, at the southern extremity of Little Cumbrae, and then 
across to Garrock Head, which is the southernmost point of Bute. 
The flood-tide which passes by the Cumbraes comes up the 
centre and the eastern side of the firth, and after passing the 
islands, flows up Loch Long, several small lochs, and the estuary 
of the river Clyde. 
The favourite place for tow-netting was in the main tideway, 
