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 limits, 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 macrampliidiscs 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 slight, 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 relatively 
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. 
