376 SKIANEMA. 



fourteen qualities here discussed, and must therefore, I think, be kept distinct. 

 The two pairs A-B and E~F are more similar. The units of the first coincide 

 in respect to nine, the units of the second in respect to seven of these fourteen 

 qualities. The pair A-B consists of the two forms described by Wilson, and it 

 must, in comparing these, be kept in mind that this author does not give the 

 measurements of all the dimensions and proportions (a-o) here discussed, and 

 of the dimensions he does give mentions only to Umits, but states neither the 

 biometric character of the variation nor the averages of the individual measure- 

 ments. As his measurements are insufficient for this comparison it is probable 

 that these two forms do not coincide in the manner indicated by the figures 

 given in the above table. However this may be, there doubtlessly exists a con- 

 siderable difference between the large macramphidiscs of these forms, the 

 length of the anchors being one seventh of the length of the whole spicule in 

 the one, and one fifth in the other. I think this difference by itself sufficient 

 to keep the forms A and B distinct. 



The forms E and F are certainly very similar. The chief differences between 

 them are that the large macramphidiscs and large micramphidiscs are larger, 

 and that the breadth of the anchors of the small micramphidiscs is relatively 

 smaller in the former than in the latter. The specimens of both these forms 

 are very fragmentary, which renders it doubly difficult to decide whether the 

 observed differences between them should be considered sufficient to keep them 

 distinct or not. In doubtful cases like this, it is, I think, better to keep similar 

 specimens distinct rather than to unite them. 



The differences between these six lots of sponges are sUght, not correlated 

 to the distance between the stations where they were obtained, and in my 

 opinion insufficient for varietal distinction. They render it however advisable 

 to describe them as different forms of Hyalonema pateriferum. These forms are 

 not equivalent, E and F being much more similar than any other pair, with the 

 exception possibly of A and B. 



SKIANEMA, subgen. nov. 



Species of Hyalonema of which the amphidiscs of one kind have relati\'ely 

 rather large, broad and low, umbrella-shaped terminal anchors. 



The collection contains three specimens of this subgenus, which belong to 

 two species, both of which are new. 



