THE ROCK-BARNACLE 75 



would take a nauplius days to travel a single mile, even if 

 it never ceased to propel itself in a straight line. But it 

 need only keep itself near the surface of the sea, to be 

 drifted along a hundred or a thousand times as fast. 



It will now be convenient to recapitulate the life-history 

 of the barnacles, and see how far Thompson and Burmeister 

 had got. Balanus and Lepas are the technical names of 

 the rock-barnacle and the stalked barnacle. 



BALANUS. 



Larva I. Nauplius. 

 Larva 2. Cypris (T). 

 Rock-barnacle. 



LEPAS. 



Nauplius (B.T). 

 Cypris (B). 

 Stalked barnacle. 



Thompson was acquainted only with the stages marked 

 T, Burmeister with those marked B ; neither knew of 

 the Nauplius stage of Balanus, which was first recognised 

 by Goodsir (p. 71). 



The Nauplius-stage of the stalked barnacle had been 

 found and figured long before the time of Burmeister or 

 Thompson, by Martin Slabber, whose Naturkundige Ver- 

 lustigingen (Recreations in Natural History), published 

 at Haarlem in 1778, is a collection of short illustrated 

 monographs of nondescript animals, executed after the 

 manner of Rosel von Rosenhof's Insecten-Belustigung, 

 (Niirnberg, 1746-55). Slabber relates that in November, 

 1767, two countrymen brought him the bottom of a cask 

 and an empty corked bottle, both of which had been cast 

 up on the seashore the night before, and which were 

 covered with stalked barnacles. When some of these were 

 placed in sea-water, they emitted clouds which rendered 

 the water turbid. A magnifying glass showed that the 

 clouds were composed of minute living bodies, one of 

 which Slabber figures as he saw it by the help of Cuff's 

 microscope, and his representation is quite recognisable. 

 Slabber had thus, without knowing it, discovered the 

 very singular larva of the stalked barnacle. He calls it 



