262 " ENDEAVOUR " SCIENTIFIC RESULTS. 



of the group which has been subjected to a similarly searching 

 examination. Of S. crenata I have seen only one or two 

 specimens, in which I found no opercula. Whether S. 

 insignis and S. pluridentata have an operculum has not been 

 determined. 



S. elongata is dealt with elsewhere in this Report, and in 

 Part I, and as I have pointed out, it agrees precisely in habit 

 with a number of other species which by Levinsen would 

 be divided between the genera Sertularia and Odontotheca. 

 If the teeth ever number other than six (as implied by 

 Hutton and Coughtrey), it must I think be only an abnormal 

 condition, which I have never met with. They are sym- 

 metrical, in so far that there are three on each side of the 

 hydrotheca, yet the two sides are not absolutely alike, as 

 the distal portions of the hydrothecae are somewhat bent in 

 such a way as to make the apertures face toward one side 

 of the colony, so that, like most Sertularice, but unlike S. 

 acanthostoma, the polypary has a distinct front and back 

 aspect. This turning forward of the hydrothecse is very 

 pronounced in some specimens, but scarcely traceable in 

 others, and when it occurs it is confined to the hydrothecae 

 on one side of the pinna. The teeth vary a good deal in 

 length, and there is a rather wide extent of the border on 

 the adcauline side free from them, while no median tooth 

 is present. 



In S. billardi, (which has the hydrothecae very different in 

 form from those of 8. elongata, and more like those of S. 

 macrocarpa and S. bidens), there are nine teeth. As in 

 S. elongata, there is a gap between those nearest the adcauline 

 margin, and as the number is odd, it follows that either the 

 two sides are not symmetrical, or that there is a median 

 tooth on the abcauline margin and four on each side. The 

 latter appears from the figure to be the actual arrangement. 



S. acanthostoma has no median tooth either on the adcauline 

 or the opposite border, but has eight on each side, which 

 correspond to those opposite them in all respects, so that 

 the denticulation is quite regular, like that of an Aglaophenia, 

 and the hydrothecae are in one plane, and both aspects of 

 the polypidom are alike. 



S. pluridentata is described by Kirchenpauer without the 

 number of teeth being specified. So far as can be judged 

 from the figure there appears to be a median tooth both on 

 the adcauline and abcauline borders, with three others on 

 each side. 



