THE BOAT. O 



filled up to the best of my memory the little sketch, and only 

 wish you could have seen the Velellas as I did, in their full life 

 and beauty." 



Two of the specimens here mentioned are in my collection, 

 and beautiful little things they are. The two plates are not 

 thicker than ordinary silver paper, but are wonderfully strong, 

 tough,"* and elastic. The oval horizontal plate, or raft, if it 

 may be so called, is strengthened by being corrugated in con- 

 centric lines, and having a multitude of very fine ribs radiating 

 from the centre to the circumference. It is slightly thickened 

 on the edges, evidently for the attachment of the tentacles. 



The perpendicular plate, or sail, does not occupy the larger 

 diameter of the raft, but stretches across it diagonally from 

 edge to edge, rising highest in the centre and diminishing 

 towards the edges, so that it presents an outline singularly like 

 that of a lateen sail. It is rather curious that the magnifying 

 glass gives but little, if any, assistance to the observer, the 

 naked eye answering every purpose. Even the microscope is 

 useless, detecting no peculiarity of structure. I tried it with 

 the polariscope, scarcely expecting, but rather hoping, to find 

 that it was sensitive to polarised light. But no such result 

 took place, the Yelella being quite unaffected by it. 



The corresponding illustration is a sketch of a raft to 

 which a sail is attached. Such rafts as this are in use in many 

 parts of the world, the sail saving manual labour, and the 

 large steering oar answering the double purpose of keel and 

 rudder. In the Velella, the tentacles, though they may not 

 act in the latter capacity, certainly do act in that of the former, 

 and serve to prevent the little creature from being capsized in 

 a gale of wind. 



THE BOAT. 



THERE is no doubt that the first idea of locomotion in the 

 water, independently of swimming, was the raft ; nor is it 

 difficult to trace the gradual development of the raft into a 

 Boat. The development of the Kraman's canoe into the Great 

 Eastern, or a modern ironclad vessel, is simply a matter of 

 time. 



It is tolerably evident that the first raft was nothing more 

 than a tree-trunk. Finding that the single trunk was apt to 



