Noor. | ACTINIARIA OF THE BAHAMAS. it 
The striation of the column is a comparatively unimportant 
character, since Aiptasias which usually present it have been 
frequently found without it, or at all events with it so faintly 
developed as to be hardly discernible, and in forms so extensible 
as this the size is not a character of sufficient importance to 
warrant a separation of species. It is possible that Duchassaing 
and Michelotti’s A. solifera is really identical with Lesueur’s 
annulata, his solifera being really distinct, but it has seemed 
advisable to unite the two forms and to retain Lesueur’s specific 
name aznulata as indicating a very evident characteristic. 
The octameral arrangement of the tentacles and mesenteries 
in A. annulata brings up a question as to the validity of Hert- 
wig’s tribe Paractiniz, which was founded (’82) upon single 
specimens, belonging to two different families, dredged by the 
“Challenger” from a depth of 1600 and 2160 fathoms respec- 
tively. The tribe is characterized by the number of the anti- 
meres not being a multiple of six; in all other respects the two 
forms which belong to it resemble Hexactiniz. In one of them, 
Sicyonis crassa, the tentacles and mesenterial pairs are 64 in 
number; 16 of the pairs of mesenteries are muscular and per- 
fect, 16 muscular and imperfect, and 32 small, only slightly 
muscular and gonophoric; their formula being evidently 8, 8, 
16, 32. Though presenting characters which warrant the for- 
mation of a new genus for its reception, yet the number of 
mesenteries may possibly be abnormal, and the discovery of 
other specimens show that the hexamerous arrangement is the 
normal one. There can be no doubt but that the form described 
here is Azptasta annulata and belongs to the genus to which it 
is assigned, and this fact lends strong support to the idea that 
the octamerous arrangement of Szcyonzs is of much less impor- 
tance than Hertwig supposed. The other Paractinian, Polyopis 
striata, possesses thirty-six antimeres, there being thirty-six 
stomidia representing the tentacles and eighteen pairs of mesen- 
teries. Hertwig thinks it is ‘most probable that we have here 
a tetramerous (octamerous ?) arrangement of the septa, but that 
a pair of septa too many has been formed in one interspace on 
either side.” It seems however quite as probable, or even more 
so, that the arrangement is really hexamerous, only half the 
mesenterial pairs of the last cycle being developed. Hertwig 
states that “no arrangement into cycles of unequal values could 
