Functions of the Limnoria Terebrans. 333 



flux of the water, and to the jiavigation of the river. The 

 Hmnoria may, perhaps, be likewise instrumental in promoting 

 tlie disintegration of drift-wood at sea, so as to prepare it for 

 becoming the food of other animals, which have no organs suf- 

 ficient for reducing it from its original state to one suited to 

 their means of apprehension. In this piece of work, it may be 

 said to be a coadjutor with the teredo and other molluscous 

 borers. But it is worthy of remark, that, through the agency of 

 the limnoria, wood is reduced to much smaller fragments than 

 it is by the Teredo. Nor must we omit to notice the possibility 

 of its being the means, occasionally, of causing the removal of 

 those serious obstacles to the safe navigation of shallow seas 

 which are caused by the masts of sunken vessels. 



But, whether we be right or wrong in our suppositions as to 

 the use it may be of in the economy of nature, we cannot be 

 mistaken in regarding the ravages of the limnoria as shewing 

 what formidable enemies to man the Creator can prepare even 

 amongst what appear to us the most insignificant of his works ; 

 and how He, who ruleth over all, effects important purposes by 

 means of the smallest, and apparently incompetent, agents. 



Leith, l&th February 1834. 



Explanation of Plate VI. 



Fig. 1. Dorsal aspect of Limnoria, magnified about 10 diameters. 



2. Ventral aspect of limnoria. The line between figs. I. and 



2. indicates the real maximum size of the animal. 



3. Transverse section of the second segment, shewing the first 



pair of feet. 



4. One of the third pair of feet. 



5. One of the fifth pair of feet. 



6. Superior pair of antennae. 

 7- Inferior do. 



8' Lateral view of the head, shewing the position of the eye, 



and the disposition of its compound corneae. 

 9. The two pairs of jaws in connexion. 



10, Inner pair of jaws detached. 



11. Mandibles detached. 



VOL. XVI. NO. XXXII.— APRIL 1834. z 



