48 



interior substance is exceedingly open owing to the large 

 size and central location of the efferent canals. Its general 

 form is that of a truncated cone, fluted on the side with 

 deep furrows, the truncated apical region being either flat 

 or infundibuliform. The large excurrent apertures debouch 

 upon the truncated surface, while the small apertures are 

 situated on the sides in the interspaces between the ridges. 

 It is a social form growing on reefs either on a smooth 

 surface or attached to corals or to other sponges. The 

 normal dimensions are a height of seven or eight inches 

 with a breadth of five inches. Glove sponges of this size 

 grow commonly at a depth of three feet only beneath the 

 surface of the water, but examples of considerably larger 

 dimensions occur in deeper waters. 



Some consideration may now be given to those special 

 conditions that are indispensable to the growth of commer- 

 cial sponges generally ; to those that are favourable to the 

 Bahama region in particular ; and to those that would 

 seem in connection with the last-named area to give 

 promise, under intelligent control, of a yet more profitable 

 development of the Bahama sponge fisheries. The con- 

 ditions of depth and temperature may be cited as of the 

 first importance in connection with geographical distribu- 

 tion of sponges suited for domestic use. Relatively shallow 

 waters, varying in depth from three or four feet to thirty 

 fathoms, represent their bathymetrical range, while a tropical 

 or sub-tropical climate, that in winter does not yield a 

 lower aerial temperature than from 63° to 70° Fahr. on a 

 marine isochryme of from 55° to 60° is absolutely essential 

 for the growth of the prime qualities. These conditions, 

 coincident with the circumstance of their both being in the 

 vicinity of, or embracing extensive archipelagoes, places the 

 two areas of the Mediterranean and Bahama sponge- 



