218 EVENINGS AT THE MICROSCOPE. 



from the particles of dust and other extraneous matter 

 which are continually cleaving to them. 



There are Spiders in the sea also. I can show you one 

 which is sufficiently common on the southern shores, 

 sprawling and crawling sluggishly among the filamentous 

 sea-weeds and branching flexible zoophytes. Here it is, 

 Nymphon by name. 



Its most prominent characteristic is the exceeding slen- 

 derness of all its parts, but especially its eight legs, which 

 are greatly lengthened, each comprising eight joints, and 

 no thicker than the finest thread. On the other hand, 

 the body is reduced to a minimum ; the abdomen, which 

 in the Spiders and Harvestmen of the land is so bulky as 

 to constitute the chief volume of the animal, is here so 

 minute that you will have some difficulty in finding it 

 at all ; it is, in fact, that tiny atom of a point that pro- 

 jects between the hindmost pair of limbs. The thorax, 

 indeed, is a little more developed; but even this has 

 scarcely any appreciable breadth or thickness, being 

 ^scarcely more than the extended line formed by the suc- 

 cessive points of origin of the limbs. 



The head, however, is distinct and well furnished. It is 

 crowned with a short column, much as in the Harvestman, 

 on the summit of which are placed four black eyes, set in 

 square ; these, under the magnifying power which we are 

 applying to them, gleam like diamonds, the light being 

 highly refracted through them. It is the high refractive 

 power of these eyes, as of those which we have lately 

 been examining, which makes them appear black ; for, 

 as I have explained, they are really transparent lenses, 

 covered with polished corneae, and furnished with the other 

 essential requisite for the transmission of the rays of 

 light to the optic nerve, or, as in this case, direct to the 

 brain. 



In front, you see, the head projects into a stout oval or 

 cylindrical proboscis, terminating in a small mouth and 



