284 



ERYLUS SOLLASII. 



lines extend towards the margin. In some adult aspidasters this radial structure 

 is well defined (Plate 2, fig. 7), in others it can hardly be made out. 



There appeal's to be a certain degree of correlation between the size of the 

 sponge and the size of its aspidasters, the latter being smaller in the small speci- 

 mens of race I, forms A and B (average length of the three largest of these forms 

 lis and 120;t« respectively), larger in the middle-sized specimen, race I, form D 

 (that average 124 ju), and still larger in the large specimens of race I, form C, 

 and races II and III. iVmong the latter those of races II and III (that average 

 150 and 152 /«) are very considerably larger than those oi race I, form C (that 

 average 128 /«), and the other smaller forms of race I. Also in their shaj^e the 

 aspidasters of the different forms differ to a certain extent, those of race II 

 being much more slender and those of race I, form C (Plate 2, fig. 25) much more 

 irregular tlian those of the others. Also in the number of the ray-spines differ- 

 0ences are observed, the rays of the aspidasters of race II bearing up to ten, those 

 of the aspidasters of the races I and III only from four to six lateral spines. 



DIMENSIONS OF THE ASPID.VSTERS. 



