104 Mr. Montagu's Description of several Marine Animals 



Length, including the posterior appendages, scarcely half an 

 inch. ^ 



Colour usually orange ; lateral appendages whitish. 



The male is very inferior in size, of a more slender form, and 

 destitute of the cirri on the anterior part of the body ; and those 

 on the posterior joints are simple, not branched as in the female : 

 in other respects they agree. 



This curious species of Oniscus inhabits the thoracic plate of 

 Cancer subterraneus t (Tab. III. fig. 1.) concealing itself between the 

 fleshy part and the shell, and forming a tumour on one side. From 

 this situation I have extracted it alive, and have kept it in that 

 state for several days in a glass of sea water. In the few of that 

 rare species of crab I have obtained, two or three of these para- 

 sitical insects have occurred, and have always been attended by 

 the male, who attaches himself firmly by his claws to the ventral 

 fins, or appendages. 



As this insect seems to be possessed of little or no locomotive 

 power, it is probable the greater part of the eggs or young must 

 perish ; for it must be in one of these states that it finds its way 

 under the thoracic shell of the crab, and there receives that 

 nourishment which in all probability is the only means of its 

 existence. 



The very disproportionate size of the sexes is wisely adapted 

 to an animal whose habitation is so confined. 



Oniscus Squillarum. 



This is another parasitical species, inhabiting the same part 

 of the prawn or pandle as the last is found to do in Cancer sub- 

 terraneus. 



The 



