176 



THE BOOK OF NATURE STUDY 



shore ; (8) the sandhoppers, leaping high into the air when the 

 tossed-up seaweed is disturbed ; (9) some sea-slater, such as 

 Idotea tricuspidata; (10) the common shore-crab, buried in the 

 sand at the floor of a rock pool ; (n) the commonest sea- 

 anemone, the beadlet, Actinia mesembryanthemum] (12) some 

 representatives of the primitive wingless insects (e.g. Anurida 

 maritima) in the cre- 

 vices of the rocks or 

 lying like floating 

 iron filings on the 

 surface film of small 

 pools. 



As another very 



FIG. 89. Acorn-shell (Balanus 

 balanoides\ enlarged four 

 times, showing curled feet 

 projecting from between the 

 (4) valves, which close the 

 top of the external circular 

 rampart. The latter is built 

 up of many pieces. 



FIG. 90. Acorn - shell 

 much enlarged. C, 

 six pairs of cirri or 

 curled legs, which 

 waft food into the 

 mouth ; P, penis ; A, 

 appendages around 

 the mouth ; V, one of 

 the four valves ; R, 

 external rampart. 



FiG.9i. Shipbarnacle 

 for comparison with 

 acorn-shell. A, at- 

 taching disc, repre- 

 senting the original 

 tip of the head ; S, 

 stalk formed from 

 an elongation of the 

 front part of the 

 head ; C, cirri or 

 thoracic legs ; Sc, 

 scutum; T,terguni; 

 Ca, carina. 



pleasant and instruc- 

 tive exercise we may 

 suggest the collection 

 of all sorts of natural 

 shore jetsam pieces of sponge, zoophytes, sea-pens, starfish, sea- 

 urchins, Aristotle's lantern, moulted shells of crabs, sea-mat, 

 bivalves and gasteropods, the egg-capsules of the buckie, mer- 

 maid's purses, and so on. These can be kept with appropriate 

 pieces of sea- weed in clean sand in a large box. By turning 

 this out on the table one can have, at any time, the beautiful 

 natural disorder of the seashore. 



