BARNACLES. 



193 



by their divergence. They resolve themselves into six 

 pairs of arms ; for each one is branched from the basal 

 joint, dividing into two equal and similar portions. Those 

 nearest the mouth are the shortest ; and each pair increases 

 regularly in length to the most distant, which are the 

 central pair when the hand is extended. Each division of 

 each of this longest and most extensile pair comprises, in 

 the specimen before us, thirty -two joints, while the shortest 

 consists of about ten, the intermediate ones being in pro- 

 portion ; so that the whole apparatus includes nearly five 

 hundred distinct articulations ; a wonderful provision for 

 flexibility, seeing that every joint is worked by its own 

 proper system of muscles. 



Moreover, every separate joint is furnished with its own 

 system of spinous hairs, which are doubtless delicate 

 organs of touch, since it has been established that the 

 hairs with which the shelly coats of Crustacea are studded, 

 pass through the substance of the latter, and communicate 

 with a pulpy mass, richly sup- 

 plied with nerves, which lines 

 the shell.* These hairs project 

 at a more or less wide angle 

 from the axis of the finger-like 

 filament, and are graduated in 

 length ; and, what is very striking, 

 as illustrating the exquisite work- 

 manship of the Divine hand, the 

 hairs themselves are compound 

 structures ; for under a high 

 power they seem to be composed 

 of numerous joints, — a deceptive 

 appearance, probably, what look 

 like joints being rather successive 

 shoulders, or projections and con- 

 strictions of the outline, — while 



* " Proo. Royal Society," ix. 215. 

 o 



HAND OF BARNACLE. 



