A REVISION OF THE GENUS STEGANOPORRLLA. 281 



As Busk had liimself dropped the earlier specific name, and 

 as later writers have accepted that given iu the diagnosis 

 (1854), I have preferred to retain the familiar name. The 

 locality " Algoa Bay/' given by Busk, does not refer to this 

 species, but to what I have called S. Buskii (see p. 272). 

 As the locality "Abrolhos Islet" stands first in the diagnosis, 

 and as, moreover, the figure refers to the species from that 

 locality (as may be concluded in particular from the form of 

 the A opercula and the presence in them of a basal sclerite), 

 it is clear that Busk's name should be applied to the S. 

 American form. In the 'Challenger Report' Busk gives 

 unmistakable figures (p. 76) of the opercula (a and b) of this 

 species, describing the two forms of zooecia ; and calls atten- 

 tion to the epithecal sclerites (''furcate spicula"). The 

 statement that the epitheca is closely adherent proximally 

 to the calcareous lamina is not correct; and the generic 

 diagnosis must be amended by stating that the cryptocyst 

 may join the distal wall instead of the basal ("posterior") 

 wall. It is at present premature to speak of the b zocecia as 

 the " fertile cells." Fig. 2 a on pi. xxiii of Busk's Report 

 is somewhat misleading, inasmuch as the b opercula are 

 shaded in precisely the same way as the zooecia which have 

 lost their opercula. 



Bif lustra crassa, Haswell,^ is given by some authors as 

 a synonym of S, magnilabris. I do not think there is 

 sufficient evidence for regarding this species as a Stegano- 

 porella. Haswell gives Membranipora magnilabris 

 in his list of species; and although the zoarial character 

 doubtless guided him in assigning* B. crassa to Bif lustra, 

 I think it would be difficult for the same writer to refer two 

 forms of Steganoporella to different genera on account of 

 differences in their habit without at least calling attention to 

 the resemblance of their zooecia. 



This widely distributed species occurs in various forms. 

 Most of those I have seen are encrusting, but (e)is Escharan, 

 as figured in the ' Challenger Report.' Smitt states that 

 » 'Proc. Linn. Soc N.S.W.,' v, 1S81, p. 38, pi. i, fig. 8. 



