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Part III — Seventh Annual Report 



As in the case of the Echinoderms the bottom- and surface-nets captured 

 most Molluscoids in August. 



Young Appendicularians (PL VI. fig. 9) were frequent in the bottom- 

 and surface-nets, especially the former. On the whole, they were small 

 when contrasted with those procured in May. C yphonautes were also equally 

 plentiful in both nets, some of the largest forms occurring in the surface- 

 net. Actinotrocha in various stages was common, and in some the tube 

 was evolved, it may be after immersion in spirit, as no further change had 

 taken place in the condition of the larva. This form was most frequent in 

 the bottom-nets, though from the beginning of the month onward it was 

 occasionally present in the surface-nets. Beyond the Bay a similar 

 fauna existed. Appendicularians, Cyphonautes, and Actinotrocha being 

 present in both nets. The first mentioned likewise occurred in the mid- 

 water net in both regions. The largest specimen (10 mm.) was captured 

 in this net near the Bell Rock. 



The bottom and surface nets still teemed with young mussels. In every 

 haul of the bottom-net they were more or less abundant, their diameter 

 ranging from 'Oil to '017 inch, while about the middle of the month one 

 or two (it may be accidental forms) were about 1 mm., and ovoid in 

 outline. Such, however, were exceptions, and might have been swept 

 from sea-weeds or other bodies by the net. The majority averaged *012 

 to 0*13 inch. Young examples of Spirialis retroversus were common in 

 this net, but they were smaller than those procured in the same net in the 

 opeu water south-east of the Bell Rock, on board the ' Garland.' Swarms of 

 larval univalves, apparently the young of Natica catena and others were 

 now present in this net, indeed they formed a feature of the mouth. If 

 some should prove to be Natica catena, then the breeding season of this 

 species extends over a considerable period, since the ribbons of sand 

 containing the ova are obtained from March onward. 



In the surface-net also the young mussels occurred plentifully through- 

 out August, their size for the most part agreeing with those found near 

 the bottom, viz., from *010 to *017 inch, the average in each series (i.e., 

 for the day) varying from 'Oil to *14, though sometimes it reached on the 

 one hand "010 inch, and on the other '017 inch. Such would indicate that 

 the pelagic mussels attain, as a rule, an average size, and then change their 

 mode of life. After preservation in spirit they resemble to the naked 

 eye grains of sand, and are easily separated from the more buoyant 

 animals by the readiness with which they fall to the bottom of the vessel. 

 Besides the pelagic mussels were other minute bivalves, probably the post- 

 larval conditions of the common mollusks of the Bay, such as Mactra, Venus, 

 and other forms, though their precise nature is at present uncertain. 

 Numerous post-larval forms of Natica were likewise present in this net, 

 and the young of Spirialis occasionally. The surface-nets in the open 

 water near the Bell Rock and south-east of the Island of May presented 

 similar forms, Spirialis, perhaps, being more abundant. The post- 

 larval mussels measured, as in the Bay, -011 to "014 inch. 



No post-larval fishes were captured in the surface-net in the Bay in 

 August, though in the open water beyond it (near the Bell Rock) pelagic 

 Afotellce, 3, 5, and 6 mm., were obtained. The great black ventral fins 

 were conspicuous. In the same net also were several Pleuronectids. 



The mid-water net during this month showed a great diminution of the 

 post-larval round food-fishes so characteristic of the previous period ; 

 indeed, gobies and Pleuronectids were most conspicuous in the Bay. 

 From the beginning of the month gobies from 3 to 10 mm. were frequent, 

 and towards the end others varying from 5 to 12 mm. appeared. Two 

 very young gurnards 5 and G mm. were captured at the end of August. 



