264 EVENINGS AT THE MICROSCOPE. 



Should it ever be your fortune to fall in with a species, 

 of Sea-mouse (Aphrodite liystrix), which inhabits our 

 southern coast a little way from the shore, you may be 

 delighted and surprised with a modification of these 

 organs, which exhibits a more than ordinarily obvious 

 amount of creative forethought and skill. I will describe 

 them in the words of the learned historians of these 

 animals, MM. Audouin and Milne-Edwards : — 



" The feet are divided into two very distinct branches,, 

 the lower of which is large, conical, of a yellowish-brown 

 hue, and much shagreened on the surface. The upper 

 branch is much less salient than the lower. We observe 

 at the foot of the dorsal shields two bundles of rigid 

 bristles : the one, expanded like a fan and applied upon 

 the shields, is fixed immediately outside the insertion of 

 those organs; the bristles which compose it are awl- 

 shaped, without teeth, slightly curved, and directed in- 

 wards and backwards ; their colour is a clear brown, 

 with golden reflections. The second bundle is inserted 

 more externally, on a tuberculous foot-stalk, and points 

 horizontally backwards and outwards. The bristles which 

 enter into its composition are very long, very strong, and 

 terminated by a lance-shaped point, of which the edges 

 are garnished with teeth curved backwards towards the 

 base. These are veritable barbed arrows, having the 

 extremities sometimes exposed, but often concealed in a 

 sheath which is formed of two horny pieces, capable of 

 opening and of closing again upon them. 



" The use of these two valves it is not difficult to detect. 

 They protect the points of the arrow, and permit the 

 Aphrodite to receive them again into its body unharmed ; 

 whereas, without this precaution, the tissues which they 

 traverse would be cut and mangled. But when these 

 weapons are deeply plunged into a foreign body, as into- 

 the soft flesh of those animals which annoy the Worm, 

 since the sheath does not penetrate with them but folds- 



