4 HiCKSON, Spechneii of Osteocella septentrionalis {Gray). 



in sections. In this respect the pinna resembles that of 

 a Virgitlaria. It is very unfortunate that the character of 

 the pinnae of the lower end of the rachis cannot be de- 

 termined, as that part of the specimen was not included 

 among the pieces sent to me. There are two reasons, 

 however, for believing that the lower part of the rachis 

 resembles, in general character, that of Virgnlaria. 



In one of the pieces, which I take to be the lowest 

 part of the rachis represented, there are three or four 

 zooids on the ventral side of the pinna so immature that 

 they have very much the appearance of siphonozooids. 



In the description given by Moss of a specimen which 

 is clearly identical with ours, it is clear that the pinnae at 

 the lower end of the rachis are, as in Vtrgularia, not fully 

 developed. 



There are no spicules either in the autozooids or in 

 any other part of the rachis. The siphonozooids are to be 

 seen on the smooth dorsal track. They appear to be 

 arranged in four or five longitudinal rows on each side of 

 this track, the siphonozooids of each row being situated at 

 distances of 3 or 4 mm. apart. I have been able to discover 

 that there are also small siphonozooids between the pinnae, 

 as there are in many species of Virgulai-ia. 



With reference to the siphonozooids, I wish to make 

 one remark before passing on to other characters of this 

 remarkable pennatulid. It is, in my experience, a very 

 difficult matter to be certain that siphonozooids are not 

 present in any part of a pennatulid, unless that part is 

 carefully examined in prepared sections. Some siphono- 

 zooids can be easily seen in the unaltered spirit specimen, 

 but others are so retracted that they can only be seen in 

 thin preparations. As an example of this, I may refer to 

 the small siphonozooids that occur on the stalk and bulb 

 of Umbellula carpenteri (5). Unless extreme care is taken, 



