MISCELLANEOUS. 53 



true position, namely, as interposed between the simple and naked hydra 

 of the fresh-waters, and the Tubularia of the sea. It participates some- 

 what of the structure of both, and the mode of its perpetuation seems to 

 connect it with the latter. 



But I doubt whether more than fragments of finer specimens have 

 fallen into my possession, though many of inferior dimensions have oc- 

 curred. 



This is one of the animals, however, after which it is vain to institute 

 a special search, as after various zoophytes whose abode we may reason- 

 ably expect to reach. Yet here does one auxiliary sometimes come to as- 

 sist us, namely, a creature the most opposite in form, in nature, and in 

 habits — the Hermit Crab. 



From the necessity of protecting part of its body, as we shall after- 

 wards see more at length, the hermit crab is obliged to take posses- 

 sion of an empty shell, which is often brought to shallow water, or almost 

 to the shore. Such shells, conveyed by the new tenant from greater 

 depths, are often profusely invested by the hydra in question ; therefore, 

 the capture of a number of hermit crabs thus sheltered, will give the ob- 

 server a fair chance of finding his object. 



The Hydra squamata dwells chiefly in numerous colonies — which are 

 always implanted on the empty shell of the Nerita, Tritonium, Murex, or 

 others of the testaceous tribes — a peculiarity that, as I am informed, be- 

 longs also to those specimens found on the coast of Ireland. 



In greatest luxuriance, the hydra consists of a stem with branches ; 

 but I have had such only on the rarest occasions, and in a diminutive 

 state, none being above four lines in height. 



The animals are single, though numerously associated, generally of 

 the palest carnation, the palest grey, dingy or pure white. A portion of 

 the largest volute of a decaying shell was invested by many hundred 

 hydra?, resembling a snow-white fleece. The shell was occupied by a 

 hermit crab. 



The colony seems to be founded originally on the epidermis of 

 the shell, whence the animal rises by a slender stalk, enlarging above, 

 which, I presume, has obtained for it, the inappropriate name coryna. This 



