DEVELOPMENT OF FLUSTEELLA HISHDA. 437 



At each of the above places Flustrella hispida grows 

 abundantly between tide marks on F ucus, and occasionally also 

 on other Algse. The colonies form characteristic, dark, mossy- 

 looking patches encrusting the algal fronds: the Fucus, 

 when growing near low water mark, is often almost entirely 

 covered with this Bryozoan, but nearer high water mark the 

 Flustrella is not nearly so abundant, nor is it so well deve- 

 loped. Young colonies occur mainly on Fucus of the same 

 season's growth. 



For the study of the larval development, colonies of one or 

 two seasons' growth taken from close to low water mark have 

 proved the most suitable. Such colonies contain abundance 

 of spermatozoa or of ova and larvae, according to the season. 

 Older colonies contain larger masses of dead zooecia, larvse 

 being relatively less abundant, while these latter are wanting in 

 such colonies as are presumably of the current year's growth. 

 Again, in colonies taken near high water mark, larvae and 

 eggs are comparatively scarce, thus suggesting that the 

 conditions of life are not so favourable as at a lower tide 

 level, possibly because the colonies are uncovered by the 

 water for a considerable part of the day. Flustrella 

 colonies containing ripe reproductive elements or larvae may 

 be recognised by the presence of numerous dark-brown 

 blotches. 



The reproductive period commences early in February and 

 continues until the beginning of August. Generally speaking, 

 it appears that spermatozoa are abundant in February and 

 March, and that they are not in evidence after the latter 

 month. Young ova are scarce early in February and 

 increase in number in March ; during this latter month 

 segmenting eggs and young larv^ are also abundant and 

 some mature larvae are present. Sections of the younger 

 portion of a colony taken in March have shown the 

 presence of segmenting eggs and larvae in the older 

 zooecia, and of spermatozoa, together with a few young 

 ova, in the younger zocecia near the apex of the colony 

 (PI. 22, fig. 1). The maximum development of young embryos 



