352 ASELLID^. 



The Gribble is one of the most destructive creatures 

 to be found amongst the whole of the articulated animals, 

 burrowing into the wood of marine erections, such as 

 piers, piles, and other works of public utility. Being the 

 only known species contained in the genus, its leading 

 characters have been detailed above, and in the generic 

 description. The male is about one-third larger than 

 the female. In general, not more than seven, or at most 

 nine, young ones are found within the incubatory pouch. 

 When the animal is alive, it contracts itself almost into a 

 ball, thus confirming the relationship of the genus to the 

 SphceromidcE. They are able to live at least a fortnight 

 within the wood, taken out of the water and placed in a 

 dry room. Each of the eyes is composed of seven or 

 eight blackish facets, one being in the centre. The legs 

 are articulated just beneath the sloping lateral margins of 

 the body, and being partly folded beneath the pereion, a 

 small portion only of each is seen when the animal is in 

 motion. The longest are the first and fifth pairs; the legs 

 of the second segment are shorter and thicker than those 

 of the first, the third and fourth pairs being similar to 

 the second ; the fifth pair is more slender, and the sixth 

 and seventh pairs resemble the fifth, but are rather 

 smaller. The terminal finger is, in all the legs, single and 

 somewhat hooked. 



Dr. Coldstream describes a peculiar organ situated 

 within the cavity of the tail, behind the branchia?, con- 

 sisting of two vesicular bodies of an oval form, attached 

 to a common peduncle. They were always found filled 

 with numerous dark-coloured granules, of an irregularly 

 round shape, which could not be detached from the sub- 

 stance in which they were embedded by tearing it up. 

 They exist in both males and females. The animal creeps 

 but very slowly, backwards as well as forwards, appearing 



