16 F. A. SMITT, 



The lateral walls of the zooecia are highly raised, and the membrano-calcareous 

 ectocyst, with the great operculum in the primary aperture, lies stretched, as in a 

 frame, fixed at their margin. This ectocyst covers a room, whose fioor is the corres- 

 pondence to the lamina, we have seen on the preceding species, although it has a 

 rnuch more complicated extension and configuration; because, through this lamina, the 

 whole zooecion is divided into two chambers, the one above the other, of which the 

 lower, particularly, is the dwelling-room of the bryozoan individuum and, through a 

 modification of the distal part of the lamina, gets its own aperture. The proximal 

 part of the lamina is a plain, horizontal plate, very prettily perforated by white-edged 

 pores. As in the preceding species, at the articulation of the great operculum in the 

 outer ectocyst, the lamina is raised to a broad, transverse denticle, sometimes, with its 

 lateral corners, uniting with the margin of the zooecion; but, from the base of this 

 denticle, it slopes downwards, almost vertically, to the floor of the zooecion, and the 

 middle part of this sloping is opened to form a round mouth of the lower chamber, 

 with raised börder, which finally is prolonged, a little cylindrical 1 ). Thus, at each 

 side of this internal mouth, the distal part of the original zooecion, also, is secluded 

 from the lower chamber, but, at each side of the above-named, transverse denticle, it 

 communicates with the upper chamber. 



As to the purpose, pursued by this dividing of the original zooecion, from dead 

 and dried specimens, of course, we can not draw any sure conclusions. In my former 

 papers 2 ), I have supposed the upper chamber of the Stegwo'poridan zooecia to be con- 

 nected, in any mode, with the reproduction. Now, another circumstance, on the Steg. 

 elegans, seems to bring that supposition nearer to the truth. This is the great varia- 

 tion of the size of the zooecia and, particularly, of their distal part. Very near each 

 other, opercula can be measured with their greatest breadth differing the one from the 

 other in variations from 0,t min. to 0,80 mm., although they retain the same half- 

 elliptical form. As the ordinary ocecia are wanting, they, very probably, seem to be 

 replaced by that enlargement; although an examination of the living state is quite 

 necessary for giving a true judgment. This is the more the case, as, without such an 

 examination, we can scarcely decide, in what relation this form stånds to the 



Steginoporella Rozierii 3 ) (Pl. IV", fig. 102). 



At the first sight, this form is very easily distinguished from the preceding by 

 its smaller size. The greatest breadth of the aperture of the zooecia I have measured 

 to about 0,2 mm. 



The only little specimen I got for examination, is dead and dried, and the outer 

 ectocyst is totally gone away; but otherwise, in the form of its zooecia, with their 

 raised granular margin, as well as in the conformation of the lower chamber, with its 



') The drawer, for the sake of distinctness, has represented this cylindre much more prolonged and its margin 

 more horizontal, than the reality. 



2 ) Krit. Fört., Öfvers. Vet. Akad. Förh., 1867, Bih., p. 48. 



3 ) Flustra Rozierii, Aud., Sav., Beser, de UEgypte, Polyp., tab. 8, fig. 9; D'Okb. (Reptescliarellind) Pai. 

 Franc. Terr. Cret., vol. V, p. 453; Busk (Membraniporct) Gat. Brit. Mus., Polyz., p, 59, tab. LXV. fig. 6. 



