106 SOME WONDERS OF THE SEA. 



Velella has a great advantage over the Porpita as far as 

 locomotion goes. The disc is oval rather than circular, 

 and across it there is an upright diagonal plate of the 

 same material, which acts after the manner of a sail. The 

 whole of the skeleton, including also the sail, is exceed- 

 ingly thin, not thicker than tracing paper, but is wonder 

 fully strong, considering its extreme tenuity. Like the 

 disc of the Porpita, both sail and float are covered with 

 radiating and concentric lines. 



Sometimes, when southerly winds have been long 

 prevalent, the Velella may be found on our coasts. I 

 never had the fortune to see a living specimen, but a 

 lady of my acquaintance once happened to be at Tenby 

 when a large fleet of Velellas was driven on shore by the 

 wind. 



No inhabitant of Tenby appeared to have seen them 

 before, but the sea-side people, with the inherent poetry 

 of the Welsh language, immediately gave them the 

 name of Sea Butterflies. My correspondent states that 

 the gelatinous membrane which enveloped both sail and 

 raft "was iridescent in a sort of vapoury transparent 

 cloud of many tinted colours, blue and pale crimson 

 predominating." With the letter a coloured sketch was 

 sent, which exactly corroborated the verbal description. 



She tried to keep the creatures alive, but utterly 

 failed, as they all died within a very short time and 

 began to putrefy, so that the only hope of preserving 

 any portion lay in removing the membranes and drying 

 the skeletons. This process was not a very easy one, for 



