114 
Mr. A. W. Waters on the 
dinal series: upon the pinnae they are absent for a yery short 
distance at the base; then a single one appears first upon the lower 
aspect of the branch ; and the series thence ascends in a close spiral. 
Afterwards the spiral arrangement becomes lost or obscured, and 
we see simply the longitudinal rows, which on the pinnae seem not 
to exceed the number of five or six. But, as M. Mereschkowsky 
has observed in the case of S. decemserialis, this limit is not to he 
considered absolutely constant; for since the fundamental arrange¬ 
ment is a close spire, the apparent number of rows of hydrothecae 
will always depend upon the thickness of the pinna they surround. 
The present species seems to be most nearly related to S. mira- 
bilis, Verrill, from which, however, it differs markedly in the nume¬ 
rous rows of hydrothecae on the main stem, these being reduced to 
two in the allied species. 
However similar all the species which havo been ascribed to 
Selaginopsis are as regards the form and general arrangement of the 
hydrothecae, I am yet doubtful whether a generic separation might 
not still be made with advantage between those forms which are 
simply pinnate and those whose branches lie in all planes or are 
disposed in a more or less irregular manner. 
XI .—On the Bryozoa [Polyzoo) of the Bay of Naples. 
By Arthur Wm. Waters, F.Gf.S. 
[Plates XII.-XV.] 
[Continued from p. 43.] 
The same plan will be followed in this as in the previous 
part, of only giving the synonyms where there is any special 
reason for doing so; but for the long list of synonyms which 
most species possess the reader is referred to the works of 
Smitt and Busk. 
Cheilostomata [continued). 
34. Aetea anguina, L., forma recta. 
(PI. XV. fig. 7.) 
ALtea recta, Hineks, Cat. of Zooph., Ann. & Mag. Nat. Hist. 3rd ser. 
vol. ix. p. 25, pi. vii. fig. 3. 
Mtea anguina, forma recta, Smitt, Krit. Fort. 1867, p. 281, pi. xvi. 
figs. 5, 6. 
?JEtea ligulata, Busk, Cat. Mar. Polyz. p. 31, pi. xlii. 
The difficulty is very great as to the position of Aetea , as it 
has relationships with the Cheilostomata and also with the 
Ctenostomata (in having a collar as seen in the Naples speci¬ 
mens, and which Smitt pointed out in 1867) ; and whether it 
will have to be placed in a new suborder (Stolonata, Claus, 
