414 On the Marine Fauna of Great Britain. 



Balanoglossus is found between tide-marks, and ascidians 

 are numerous and large in the same region. In the sur- 

 rounding waters swarms of Salpaj occasionally appear, now 

 and then accompanied by Doliolum. 



Amongst fishes, eels are abundant between tide-marks, and 

 •wrasses at the margin of the rocks, gliding here and there 

 like dark shadows under the tangles. Black gobies are 

 frequent in the tidal region ; while in the inshore waters 

 whiting -pout, red mullets. Hippocampi^ gattoruginous 

 blennies, rainbow, cook, and otlier wrasses, Serranuft, small 

 blue sharks and congers, are common. " Schools" of pilchards 

 break the surface of the water like a lieavy shower of hail in 

 certain areas, and mackerel are abundant. 



The marine mammals, viz. seals and cetaceans, are much 

 less common than in the north and north-west. 



Each of the four areas has certain forms common to all, 

 but at the same time each has species that occur sparingly or 

 not at all in the others, though it is true great caution is 

 required in regard to the latter statement. 



The eastern coast is distinguished rather by the absence of 

 forms that are present in other areas, though the abundance 

 of such as Lucernaria, Ilijjpasterias, Echiurits, ^lagelona, 

 Pelonaia, and the remarkably persistent profusion of food- 

 fishes are also features of moment. Towards the north, as 

 in the Moray Frith, again, we encounter southern forms that 

 show no connecting links along the eastern shores, but the 

 distribution of which seems to point to the view of Canon 

 Norman that such may have travelled from the west round 

 the north of Scotland, or in some cases may have passed from 

 the northern shores of Europe in a westerly direction. 



1 he western coast is in the main southern in its fauna, 

 though the abundance oWarT/ophyllia and Poniatocerus triqueter 

 within tide-marks, and of Velella, lanthina, and the Salpse, 

 together with the frequency of seals and whales, are distin- 

 guishing features. Tlie invertebrate marine fauna and fishes 

 niay have spread from the south and the west. 



That the warm currents of air and water along the western 

 shores are the main factors in accounting for the special fauna 

 of the region is evident, and they carry that fauna to the 

 Shetland Islands, and, passing through the various gaps, lave 

 both sides of the land, so that the eastern fauna of the latter 

 more resembles that of the west. Thus the southern types 

 like Adambia, that are found in the Moray Frith, may have 

 spread from the same centres, though the commingling of 

 northern species (for example, Lumpenus) proves that other 

 centres along the northern shores of Europe must have con- 

 tributed. 



