GENUS CERAPUS. 51 



new genus, was found amongst fuci on the sea beach at 

 Egg- 1 J arbour in considerable numbers. In its mode of 

 life it bears some resemblance to the Pagurii, inhabiting 

 a cylindrical tube; but the circumstance of its inhabit- 

 ing a foreign body is the only point of similarity between 

 them. To the genus Caprella it approximates by the 

 form and disposition of the head with the antennae; but 

 differs from it in essential particulars, as in the form of 

 the tail, number of joints of the body, and position and 

 form of the feet. With the genera Talitrus, Gamma- 

 rus, Sec. it is related chiefly by the incurved tail and re- 

 flected hind feet, but the caudal appendices, as well as 

 many other important parts, are totally dissimilar, these 

 appendices are not rigid and spinose as in Gammarus, but 

 flexible and lateral as in Cymothoa. Its proper situation 

 in the system of Latreille will be with the family Gam- 

 marinas and intermediate between the genera Gammarus 

 and Caprella. But in the excellent modifications of Dr. 

 Leach it will be placed in his family Podoceridae, next 

 to his recently discovered genus Jassa, to which indeed 

 it might be referred, as far as I am able to judge from 

 the brief description that has been given of that genus, 

 but for the two-jointed thumb, and other minor charac- 

 ters. 



This little animal is very active, running with great 

 facility amongst the branches of fucus, sertularia, &c. 

 although encumbered by its tube, and what is extraordi- 

 nary, making use of its four antennas only as feet; the 

 proper feet are all included within the tube, with the ex- 

 ception of the two anterior pairs, which are only used to 

 seize its prey and convey it to the mouth. Feeds prin- 

 cipally upon the animals of Sertularia? 



The tube is always proportioned to the size of the 



