FLORIDAN BRYOZOA. 71 



The close relation existing between the two above-named forms, in spite of their 

 great differenee in size and outer appearance, incontestably is proved by the very same 

 form of their zooecial apertures. 



The Discopora pusilla is to be reckoned among the smallest escharines. It is of 

 a shining yellow-whitish hue; the colonies in patches of only a few millimetres or 

 raised into a calcareous-white cylindrical stem, about 3 mm. high. The convex front 

 wall of the zooecia, in a radiating manner, usually prickled by small depressions, rem- 

 nants of the primary pores, or at last, in the highest degrees of calcification, granu- 

 lated by warts, sometimes, on its side bears an acute, lateral avicularium, whose hori- 

 zontal aperture points outwards. This, however, seems to be of a very rare occur- 

 rence, when on the contrary the oral avicularium is constant, in the same position as 

 in the preceding species, but more projecting över the zooecial aperture, in that as well 

 as in other respects, in the nearest resemblance to the northern Discopiora contigua, 

 with which this form, indeed, is closely allied, although once *), by a mistake, in not 

 giving the form of the zooecial aperture its worthy attention, I placed that northern 

 Discopora at the side of the true Cellepora?. 



The typical Discopora albirostiis, in- a fresh condition, is readily recognizable by 

 its grayish-brown colour, with blackish-brown opercles in the zooecial and avicularian 

 apertures, against Avhich the calcareous white, projecting rostra show off. The zooecia 

 in the growing edge of the colony are elongated ovate, in most respects presenting the 

 greatest resemblance to the Tasmanian Cellepora (Discopora?) bispinata, as figured by 

 Busk, although I dåre not to identify them with that Tasmanian species, as, in this 

 state, the Floridan form seems to be of much greater size and has a much more de- 

 veloped rostrum, with an avicularian aperture, which, certainly, would not, by Busk, 

 have been described as »a very minute». 



In the middle of the colony, the celleporine growth has raised the zooecia, hea- 

 ping them irregularly över each other, and, then, this form in all points corresponds 

 with the Patagonian Cellepora (Discopora) mamillata, as described by Busk, particularly 

 as the surface of the colony here, also, sometimes is »studded with mamillary projec- 

 tions»; but the figures, given by that author, present a more acute mandible of the 

 rostral avicularium, and, in the description, he says that organ to be placed on the 

 interna! face of the rostrum, whereas, in the Floridan form, the aperture of this avi- 

 cularium is placed laterally. What he tells of »a conical spine in the opposite side of 

 the mouth», here also will be found; but this is nothing else than the rostrum of an 

 overgrown zooecion in the layer beneath. Thus, at present, we can not identify the 

 Discopora albirostris with the description of any living species, and, perhaps, the two 

 cited synonyma once will be joined to the Tertiary Cellepora (Discopora) ceratomorpha, 

 Reuss, or to the Cellepora (Discopora)' cucullina, Michelin, but for that purpose, I 

 think, a new examination of the named fossils will be necessary. 



In iinishing its secondary zooecial aperture, the Discopora, albirostris, sometimes, 

 at the side of the avicularian rostrum, produces the margin of the aperture in a lower 



l ) Öfvers. Vet. Akad. Förh. 1867, Bih., pgs. 31 and 189. 



