788 Proceedings of Royal Society of Edinburgh. [sess. 
About the beginning of March early stages (2 mm.) began to 
appear. These developed during the summer months, and reached 
maturity in September and October, when they produced an 
autumn generation. The breeding season apparently extends over 
about two months, as a mixture of early stages and large adults 
are usually found together. 
Sagitta was very scarce up to the end of June — usually only 
one or two specimens in the nets, and it was frequently absent. 
About the middle of July it became fairly common, but was scarce 
during August and September. In July the specimens taken were 
intermediate stages (5-10 mm.), and large adults were entirely 
absent. In September the specimens were about 10-15 mm. in 
length. 
At the beginning of October early stages began to make their 
appearance, and during that month large adults (20 mm.) and 
early stages (3-5 mm.) were present, hut they never became 
common. 
On 6th November Sagitta suddenly became abundant, and the 
increase in quantity was probably due to a fresh supply coming 
up the firth from the south. This shoal consisted of adults and 
intermediate stages. After the middle of November Sagitta be- 
came scarce, and continued scarce till the end of the year. In 
December only large specimens (15-20 mm.) were seen. 
The adults which are found in the spring of the year are larger 
than those which are found in the autumn. The spring race is 
about 20-28 mm. in length, and the autumn race is about 
15-20 mm. 
CRUSTACEA. 
(See Report by Dr T. Scott, page 792.) 
POLYZOA. 
Cyphonautes. 
In 1902, Cyphonautes was taken from the beginning of August 
up to the end of December. It was common during August, 
abundant on 8th September, but scarce towards the end of the 
month. It was common on 4th October, but very scarce during 
