98 A HISTORY OF RECENT CRUSTACEA 



afferent opening on either side, by their powerful move- 

 ments bring it back to the branchial cavity. The two 

 ridges on the maxillipeds, which are often densely fringed 

 with hairs, meet in front and form a triangular break- 

 water which prevents the streams intended for the brau- 

 chise from entering the mouth-opening. 



Of the rock-haunting species of the genera Plagusia, 

 Latreille, 1806, and Goniopds, de Haan, 1835, Krauss 

 speaks with a sort of admiration. At low tide they come 

 bustling out of their crannies in ho.ts. By help of their 

 soft elastic bodies, and their limbs cut out for the veiy 

 purpose, they clamber over rough blocks and steep sides 

 of rock, jump from one crag to another, and creep into 

 the most inaccessible crevices. They are not very swift, 

 but very canny, so that on their own ground, in spite of 

 their multitude, it is almost impossible to catch any of 

 them. In the fear of pursuit they will let themselves drop 

 several feet from one ledge on to another, or plunge a 

 fathom down into the sea and paddle off to the nearest 

 rock. Acanthopun clavimanus, de Haan, is a tiny species 

 nearly allied to Plctgiisia, but with different habits. It 

 lurks under stones, and it may seem a light matter to turn 

 over a stone and catch it, but before the stone is well over 

 the crab will have vv hisked to the other side, and when at 

 length it has been pinned fast, it is no easy task to drag 

 away its thin body and clinging talon-like claws without 

 breaking them. The name of this genus having been pre- 

 occupied, it has been changed by Miers to Leiolophus. 



Plagitsia contains species that come from the Atlantic 

 and Pacific, and some of these have been taken in the Medi- 

 terranean under circumstances worthy of note. In the 

 winter of 1873 an iron vessel entered the port of Mar- 

 seilles. It had come from PondichSry, by way of the Cape 

 of Good Hope, having had a long and stormy voyage in 

 the most rigorous season of the year. To the iron plates 

 of this ship had become attached a little forest of algse and 

 barnacles; and living among these were a number of 

 higher Crustacea of exotic origin. Two of the specimens 

 were found by Professor Catta to belong to a new species 



