General History of the Marine Polyzoa. 295 



characteristic f'acies of the latter. In the specimens from Port 

 Elizabeth which I have examined, these avicularia, which are 

 elevated and very constant in position, are generally present ; 

 their absence is quite exceptional and rare. As, however, 

 Busk mentions that they occur on some of the ocecial cells we 

 must not attach too much weight to their absence from the 

 zooecia in the single specimen on which the ' Challenger ' 

 diagnosis is founded. 



But there are other differences between the two forms which 

 are more significant. In the ocecial cells of Busk's species 

 the " pore " is said to be " reniform and placed low down on 

 the front," and the latter character is again referred to as " an 

 exceptional feature." Nothing of the kind is to be met with 

 in the South-African form. The ocecial cells are distinguished 

 by their size and more massive character and by the shape 

 and size of the orifice ; in all other particulars they agree with 

 the zocecia. The suboral opening occupies the same position 

 as in the ordinary cells, immediately below the bridge, and it 

 is roundish and not reniform. It is difficult at first sight 

 to understand how the " pore " could be placed " low 

 down on the front of the cell ; " but supposing it to be so, we 

 have an important difference between the ' Challenger ' and 

 the African forms *. There is no figure of the ocecial cell 

 in the ' Challenger ' Report, nor does it contain any reference 

 to the primary aperture. 



On the whole, and taking into account the general similarity 

 of most of the leading characters and the presence in both of 

 the minute peculiarity, the pectinate ridge or u denticle," it 

 will be better to refer the present variety to Busk's species, 

 of which it will rank as a form — Africana. 



I have placed this species provisionally in the genus Sckizo- 

 porella. 



The genus Adeonella, as constituted by Busk, is indistin- 

 guishable from Adeona 7 as indeed he virtually admitsf. The 

 whole group requires further investigation. 



The present species bears a close resemblance in many of 

 the leading characters to the Eschara Pallasii, Heller, which 

 I have referred to the genus Scliizoporella on account of the 

 marked sinus on the lower margin of the orifice J. But ocecial 



* In his interesting observations on Adeonella, in his ' Supplementary 

 Report on the ' Challenger ' Polyzoa,' Waters states that the " pore " " is 

 placed so low down in Adeonella Atlantica that from an external exam- 

 ination it would be supposed that it opened into the zooecial cavity " 

 (p. 33). 



t '' As regards the general zooecial characters there is no difference 

 whatever between Adeona and Adeonella " (Busk, ' Challenger ' Report, 

 part i. p. 183). 



\ " Polyzoa of the Adriatic," ' Annals ' for March 1886. 



