454 



Prof. J. C. Ewart. On the Natural and [Mar. 27, 



Asterias, Astropecten, Ophiura, Echinus, Antedon, and others — -a few 

 Crustacea — Pagurus, Nephrops, Palasmon, Cancer, and other crabs ; a 

 few sertularians and actinozoa, chiefly the common Alcyonium. 

 Compared with the spawning-beds examined during the autumn in 

 the Moray Firth, the Ballantrae Bank is peculiar in having as far as 

 our experience went a very limited coating of sea-weed and 

 sertularians. The fishermen at Ballantrae reported that owing to 

 recent storms the sea-weed is less abundant now than it was some 

 years ago. 



The absence of sea- weed cannot be accounted for by beam- trawling, 

 for so far as I could learn trawlers are careful to avoid the bank lest 

 they destroy their nets. Perhaps the spawning-bed might be 

 improved if it were possible to increase the amount of sea-weed and 

 sertularians. 



By taking soundings over the bank in various directions it was 

 ascertained that it consisted of stones, shells, gravel, and coarse sand, 

 and that the depths varied from 7 to 12 fathoms. Between the 

 bank and the shore — a distance of about a mile — the bottom consists 

 chiefly of sand and broken shells, and the depth, at some points 

 8 fathoms, diminished sometimes rapidly, sometimes slowly as the 

 shore was approached. The outer edge of the bank shelved at most 

 points rapidly until a depth of 17 fathoms was reached, and at this 

 depth the bottom consisted of fine soft mud. 



While, on the east coast spawning grounds examined during the 

 autumn, the surface temperature in most cases varied from 53° F. to 

 55° P., and the bottom temperature from 52° F. to 54° F. even at a 

 depth of 40 fathoms, the temperature at the Ballantrae Bank, during 

 the early part of March, varied from 42° -8 F. to 43°'8 F. at the 

 surface, and from 43°'5 to 42°*8 F. at the bottom. 



The corresponding surface temperature, however, on the east 

 coast during the week ending March 8th was from 2° F. to 3° F. 

 lower than at Ballantrae, and even the water in Rothesay Aquarium 

 was lower by 1° F. than the water at Ballantrae. As in autumn the 

 temperature is believed to have a great influence in determining the 

 movements of the herring, so it may influence the selection of 

 spawning grounds during the winter. 



During the autumn we found in the neighbourhood of all the 

 spawning-beds in the Moray Firth a remarkably rich surface fauna, 

 in fact on fine days the surface literally swarmed with life. In 

 addition to the millions of medusoids and ctenophora there was an 

 endless number of crustaceans (some of them at a very early stage of 

 development), larval echinoderms and molluscs, ascidian tadpoles, 

 and other minute pelagic forms. On the other hand, on the Ballan- 

 trae Bank, even when the surface was perfectly smooth, we only 

 succeeded in taking a few entomostraca with the surface-net. There 



