312 Mr. A. Hancock on a Burrowing Barnacle 



multitude of very long setse arranged in double rows along the 

 surface next the mouth. These setae diverge, so that when the 

 cirri are spread out, the tips of the setae of the adjoining cirri cross 

 each other, making a very complete net which the Cirripede is for 

 ever spreading out and sweeping through the water in the direc- 

 tion of the mouth. Its prey is thus secured, and nothing can 

 escape that comes within the range of this simple and beautiful 

 apparatus. It is not then by currents produced by the cirri, as 

 usually asserted, that these creatures obtain their food ; the feet 

 form a prehensile net of the most efficient nature, and the only 

 currents produced result from its action. 



In habit, too, this animal differs from all known Cirripedes ; 

 none I believe but this species bury themselves in hard calca- 

 reous bodies : some indeed partially conceal themselves in foreign 

 substances, and all may be said in a certain sense to be parasi- 

 tical. Tuhicinella and Coronula are well known to sink deep into 

 the skin of whales ; but in both cases the whole of the valvular 

 or upper portion of the animal is exposed ; and as both are well 

 protected by their shells, it is evident that this habit is not for 

 defence, the object apparently being to avoid that resistance of 

 the surrounding element occasioned by the rapid movements of 

 this huge animal, and the consequent difficulty there would be 

 of maintaining their hold of its smooth, contractile surface. 

 Other genera, Prygona, Crusia and Acasta, are found concealed 

 in corals and sponges ; none of them however excavate : these 

 bodies simply grow round the Cirripede, and as it augments in 

 size, which it does by increasing upwards, so does the coral or 

 sponge advance with it. Lithotrya is the only genus of the class 

 that has been described as actually excavating a habitation in 

 hard calcareous bodies; there is reason however to doubt the 

 fact, as we shall see by carefully examining Mr. Sowerby^s own 

 figures in his ' Genera of Shells.^ This creature is a pedunculate 

 Cirripede, and is stated to have at " the base of the peduncle a 

 shelly appendage." For the moment granting this to be true, 

 it is evident that the holes it occupies, if made by itself, can only 

 have been formed by either this appendage, or by the base of the 

 pedicle before the shelly appendage was secreted. But on refer- 

 ring to the figures just alluded to, it would appear that neither 

 hypothesis is correct. In one of these figures there is very cor- 

 rectly delineated a couple of Serpulce adhering to the under sur- 

 face of the basal appendage. Now it is pretty clear, that were 

 this appendage used as a rasping surface, no Serpula could exist 

 as represented ; and were the excavations effected before the for- 

 mation of this appendage, it must necessarily partake of the 

 shape of the base of the newly-formed chamber to which it would 

 be closely adherent, as in the parallel case of Hipponyx : it would 



