CONTRIBUTION TO AN EVALUATION OF THE SEA. ol7 



to grow to a good-sized colony and give off larvae within a period of not 

 more than 8 weeks. From the observations made there is no doubt that 

 this species passes through several generations during the summer and 

 autumn, and indications were given that the most rapid growth occui's 

 during August and September. In one case more than 100 zooids were 

 counted in a colony not more than a fortnight old. Another species ot 

 Bugula has been foimd to grow colonies 4 cms. high and 2-5 cms. wide in 

 15 weeks. Very large colonies of a Bowerbankia species of an age not 

 more than 9 months gave off a great number of larvae, and in another 

 experiment a colony 4-5 cms. high and 2-5 cms. wide was obtained at an 

 age not greater than 15 weeks. Scrupocellaria reptans formed good- 

 sized colonies in less than 7 months ; Memhrani'pora memhranacea grew 

 to a circular colony 6 cms. in diameter within 12 weeks, Lepirilia palki- 

 siana circular colonies 1-1 cms. in diameter within 8 weeks, and 3-1 cms. 

 in diameter within 23 weeks. CeUidaria neritina grows into huge colonies 

 in the inner basin at the Great Western Docks in a year. 



RATE OF GROWTH IN SOME CRUSTACEA. 



A few observations have been made on members of the Crustacea, 

 mostly of the sedentary forms. 



Balanus balanoides attains to full size in a year and gives off larg"e 

 numbers of nauplii at this age, but there does not appear to be more 

 than one breeding season, namely, in the late winter months. Other 

 species of Balanus, however, have been found to grow to a large size in 

 less than a year. Especially interesting results have been obtained in 

 this group by examining the bottoms of ships in dry dock and obtaining 

 information from the captain of the ship as to when the ship was last 

 scraped and painted. From the information obtained in this way it has 

 been found from independent data that Conchoderma virgata grows to a 

 good size and gives off nauplii within from 4 to 5 summer months, and 

 Lepas atuitifera and L. hilli within the same period. Conchoderma 

 aurita grows to a large size, namely, 7 cms. long, within 5 months, 

 but was not found with embryos or nauplii when examined. This rapid 

 growth of Cirripedes is well known to some captains of sailing vessels, 

 who are constantly sailing the high seas in relatively slow-moving boats, 

 for there is apparently a limit to the speed of the boat on which Lepas 

 and Conchoderma will grow. The vessel on which the specimens 

 mentioned above were obtained had travelled mostly at 6 to 8 knots I 

 was told, hence the limit of speed for their gTow^th must be something 

 greater than this. 



