BEFORE THE DAWN OF ART 283 



burrowing worms, for long sponge-spicules radiate 

 out in all directions, forming an effective chevaux de 

 frise either at the mouth of the shell or all over the 

 body of the builder. 



Another extraordinary instance of unconscious 

 skill is to be found in the shell of a species of Psam- 

 mosphsera dredged by Mr. Earland on the Gold- 

 seeker in the North Sea in happier days than these 

 (1915). This creature, which lives on very muddy 

 parts of the sea-floor, uses long sponge-spicules 

 (2-3 mm. in length) to form the foundation-poles 

 of an open framework or chamber. " The open 

 spaces in the wall are then filled in with fragments 

 of spicules carefully selected for length so as exactly 

 to fill the spaces that are to form the walls of the 

 test, an awkward triangular terminal space being 

 frequently filled in with a truncated triaxial spicule." 

 The creature lives in its roughly spherical house, and 

 the projecting ends of the long spicules serve as 

 "catamaran spars" to support the whole on the 

 surface layer of the ooze. And the wonder of adap- 

 tation does not end here, for we read that a second 

 and often a third individual will in the building 

 of its house make use of the extreme ends of long 

 spicules which project from its neighbor's construc- 

 tion. Two or three individuals united in this way 

 by their " catamaran spars " remain entirely distinct 

 organisms, " their only connection with one another 

 being a purely utilitarian one, the association 

 offering greater resistance to the mud than a single 

 individual can attain." It is, as Mr. Heron-Allen 



