St. Andrews Marine Laboratory. 45 



bottom-nets the species occurred, the larger being most plen- 

 tiful in the former. Many (f inch in diameter) seem to have 

 shed their ova. Throughout August small examples from £ 

 to \ inch were most abundant in the surface- and midwater- 

 nets, while the free ova were in various stages, and many of the 

 larvae had only recently escaped. The very young forms 

 presented the trumpet-like projection of the mouth, and with 

 the ova were most plentiful in the bottom-nets. During 

 September they swarmed in the surface- and midwater-nets, 

 ranging from | to ^ inch in polar diameter, and they were 

 accompanied by ova and larvae. Only a few of the same size 

 and some larvae were captured at the bottom. The collections 

 made in the midwater-net afforded a contrast with those ob- 

 tained e. g. in midwinter, the great size and beauty of the 

 species at the latter season being noteworthy. They became 

 rare in the surface-net in October, but myriads, ranging from i 

 to j% inch, still frequented the midwater; while a few accom- 

 panied by ova and larva? appeared in the bottom-nets. Only 

 a very few Plewobraehue were captured in the surface- and 

 bottom-nets in November, but many of large size appeared 

 in the midwater-net. In December they were found at the 

 surface in considerable numbers from § inch downwards along 

 with ova ; indeed, at no period of the year were finer examples 

 obtained. They ranged from |- to ^ inch. A few also 

 occurred in the bottom-net. As the cold season advanced 

 they had a tendency to seek the deeper parts of the water. 



It is thus apparent that many of these Ctenophores (Pleuro- 

 brachia) spawn in summer and attain their maximum size 

 the following year, the adults gradually disappearing after 

 shedding their ova. At no period, however, is the water 

 devoid of them, and throughout the greater part of the year 

 small forms are mingled with the larger. In Pleurobrachia } 

 therefore, as in certain fishes, the spawning-period is evidently 

 extended, that is, some are early mature, others considerably 

 later, so that great irregularity in size is found at any given 

 period. 



Large specimens (3^ inches) of Beroe ovata, Esch., 

 occurred in midwater at the commencement of the year along 

 with young, the former only being obtained in February. 

 Very young forms, j% inch again, appeared in April, showing 

 that some ova were probably shed late in autumn *. Ex- 

 amples of moderate size were occasionally captured in May, and, 

 like Pleurobrachw, sometimes injured the postlarval fishes in the 

 midwater-net. In June and July Beroe became more abundant 



* At Naples the deposition of ova is given as from November till 

 June (Mittheilungen Zool. Stat. Bel. viii. p. 3!:>0). 



