486 HYATT'S REVISION OF THE 



months. A more limited fishery, however, is still carried on at Anchor Keys, some thirty- 

 five miles outside of Cedar Keys, and in other places where the water is stiller, clearer, and 

 warmer than nearer shore. 



The commercial grades coincide very closely hei'e and in Eui'ope, but it is quite easy 

 to show that each of them may be considered a distinct species if one has an inclina- 

 tion to multiply in this direction. The grades are Glove Sponge {Sjjonr/ia officlnaUs), 

 sub-species tuhul'ifera, Wool Sponge {Sponr/ia equina), sub-species fjossypina, and Yellow 

 and Hard Head, both nnder the name of {Spongia agaricina) sub-species corlosia. 

 These correspond with remarkable accuracy to the three principal grades of commercial 

 sponges in Europe. These are the Bath Sponge, Spongia officinalis, the Horse Sponge, 

 Spongia equina, and the Zimocca Sponge, Spongia agaricina. This result, in which three 

 species appear on both sides of the Atlantic as representing alone the marketable qualities 

 of the genus Spongiti, becomes of double interest when these varieties, or local species as 

 they might be called, are compared one with another. It is then found that the aspect 

 of the surface is closely similar in each of the three ; that subspecies tubiiJifera represents 

 Spongia officinalis, sub-species gossyjmia offsets Sjwngia equina in the same way, and 

 lastly, sub-species corlosia has the same relation to Spongia agaricina. The general com- 

 parison of the figures in the plates will show this well enough ; but in order to make it 

 more convincing that such a relationship is not the result of an artificial arrangement, it 

 becomes necessary to describe some of the facts more at length. 



First, their similarities of surface and aspect are precisely the same as those which ex- 

 perience has led me to adopt in the designation of species in this group. Thus if they had 

 occurred in different parts of the same sea, I should not have hesitated to unite them. 



Secondly, their differences can be accounted for by the difference in habitat, and are of 

 varietal and not of specific value, according to the accej^ted use of the term species. 



For establishing the first proposition, it is only necessary, as previously remarked, to con- 

 sult the descriptions of the genus Spongia and the figures. The second proposition, how- 

 ever, requires more attention. 



The whole groujj of Keratosa is confined to seas, in which the differences observable 

 between the winter and summer isotherms are not excessive. None are found north of Cape 

 Hatteras and the Islands of Bermuda, and doubtless a similar limit occurs to the southward 

 of the equator ; at least it is a noticeable fact that the only specimens in the Museum of 

 Comparative Zoology are from the Island of Fernando Noronha. On the Pacific shore, 

 Southern California and Chili are the extreme points so far known. On the opposite coast 

 of the Atlantic they are recorded from England to the Cape of Good Hope, and also at 

 the Island of Teneriffe. In the Indian Ocean they are found all along the east coast of 

 Africa, at the Mauritius, and on the shores of India. They have been described from the 

 southern part of the sea of Ochotsk, on the Asiatic continent, and specimens are not uncom- 

 mon on the coasts of Australia and New Zealand. In the Pacific they have been found at 

 the Kingmills Islands, and Hawaiian Islands. The extreme outh'ing form to the north on 

 both sides of the Atlantic is the excessively coarse Dysiclea frag His, with its fibres loaded 

 with debris. Those from the Cape of Good Hope and Southern Australia also belong to the 

 coarser genera. The species cited by Milducho Maclay from the sea of Ochotsk, seems to 

 be one of the Phyllospongidse, but there is no analysis of the characteristics of the skel- 

 eton, only the external form being described and figured in his article on the sponges 



