42 PELAGIC FAUNA. 



the north, of the purple lanthina, of Velella and of Salps on the 

 west, and of Cydippe, Lesueuria and Appendicularians, on the 

 east, indicates certain regional distinctions. 



Though not strictly belonging to any special group or to 

 any special season, the pelagic mud carried by the bottom-water 

 plays an important part in feeding the sedentary mollusks, 

 ascidians, cirripedes and other fixed types. It is only necessary 

 to examine the stomachs of ascidians and of edible mollusks, 

 such as the oyster and the mussel, to observe the large number 

 of Infusorians, Diatoms and other Algae, the abundance of 

 spouge-spicules and organic matter of various kinds, which 

 have thus been swept by currents in their neighbourhood 

 amidst a plentiful supply of mud and sand. 



Pelagic Life during the various Months. January. It is 

 unnecessary in the present work to go fully into the nature of 

 the pelagic fauna during each month : the salient features 

 alone will be alluded to. Thus in January the floating eggs of 

 food-fishes were for the most part absent, as were also the larvae, 

 though young sprats were occasionally found near shore. Pro- 

 minent amongst the mollusks was Spirialis. Crustaceans were 

 in great force, such as Thysanopods, sessile-eyed forms (e.g. 

 Parathemisto, which attained its maximum this month), with 

 swarms of Copepods. The arrow-like worms (Sagittce) were 

 often in great profusion, indeed it was in January that the tide 

 stranded them on the west sands many years ago, when first 

 found in Scotland by the lady to whom the "St Andreivs Fauna" 

 is dedicated. They were observed to sparkle along the line of 

 the retiring tide in the setting sun like needles of glass. The 

 equally translucent Tomopteris, an annelid of great beauty, was 

 also very common. Numerous jelly-fishes likewise thronged the 

 sea, such as Tiina, Stomobrachium and Aglantha, with the 

 Ctenophores — Cydippe, Lesueuria, and Beroe. The mitre-like 

 Aglantha was one of the most characteristic jelly-fishes of the 

 winter months from January to April, and was frequently in 

 great numbers. Of Infusorians, Geratium tripos, a phospho- 

 rescent form, was in abundance, and Radiolarians occurred 

 occasionally. Amongst plants, diatoms and the lower algoids 

 were frequent — with a few Rhizosoleniae. The sea is thus very 



