1 14 Glimpses of Marine Life on the Forth. [Sess. 



hardly distinguishable from medusae or jelly-fishes. The latter 

 constitute a phase in the life-history of certain coelenterates. 

 Four species of medusae are tolerably common, and their trans- 

 parent gelatinous bells are frequently cast ashore. Of these, 

 Aurelia is distinguished by four purple crescentic bands : its 

 immediate parent, the alternation of generations being very 

 marked, is a fixed, plant -like organism of the Sertularian 

 type. 



On the Mediterranean the writer has seen the beautiful 

 Portuguese Man-of-War. This is really a colony of hydra- 

 like zooids, one of which is greatly enlarged and modified, 

 and serves as a float to support the others. A specially 

 adapted zooid also plays the part of inflator. Velella is 

 another allied organism common on the Mediterranean. In 

 appearance it resembles a small sundial. The ridge or crest, 

 as in the Portuguese Man-of-War, acts as a sail, and it is 

 interesting to watch a fleet of these organisms bearing down 

 towards one's ship like a miniature armada. The disc of 

 Velella is cellular and semi-transparent; the nutritive zooids 

 are suspended from its lower surface. Many of the medusae 

 are provided with formidable organs of defence in the shape 

 of stinging threads, which are emitted when the animal is 

 excited. 



A smaller organism, nearly related to the medusae, Beroe 

 ovata, the sea lemon, one of the Ctenophora, is at certain 

 seasons found in considerable numbers in the Forth. It is 

 globular in form, beautifully transparent, and marked by eight 

 meridional lines. These iridescent bands are the ctenophores, 

 — comb-like rows of fine cilia or motile plates, that by their 

 movement give rise to a wonderful play of colour. A living 

 sphere lit up by arcs of gleaming splendour, it is impossible to 

 convey in words any adequate idea of the diaphanous beauty 

 of Beroe. Pleurobranchia, the sea gooseberry, plentiful in 

 summer, looks like a smaller edition of Beroe: it is so 

 transparent as to be almost invisible in water. 



The sea- anemones are too well known to require descrip- 

 tion. Two species are exceedingly common — the smooth 

 anemone {Actinia) and the thick-horned Telia. The latter 

 is the larger of the two ; out of water it presents a rather 

 unsightly appearance, but when its tentacles are expanded 



