FLORIDAN BRYOZOA. 29 



Hab.: Pourtales hane speciem sat frequentem cepit in prof. 10 — 48 orgyarnm 

 viventem. Mortuam e prof. 471 org. eam sustulit. 



In constituting this a new species, I have made it alrnost only because of the 

 colonial form, and, consequently, I regard it rather a local variety; but in the Floridan 

 sea, where it seems to be very common, at least in the numerous specimens I got for 

 examination, it never presents that broad, foliaceous growth of Porina (?) sulcata, as 

 described by Milne — Edwards *) nor that of Porina (?) decussata, as described by Bitsk 2 ). 

 But in comparing it with these descriptions of the Australian species, in the strueture 

 of the individuals, it is very easy to see, how nearly it agrees with them. The 

 gravest objection against its specifical unity with this form would be the cirenmstance, 

 that neither Milne — Edwards nor Busk has remarked anything of the median pore; 

 but, as the value of that character, by those authors, was not so fully appreciated, as 

 it is now, we are, perhaps, allowed to suppose, that it has been overlooked by them; 

 and, in the older zocecia, the named pore very often is evanishing. Now, it is necessary 

 very carefully here to distinguish the different forms, because, in the neighbourhood 

 of this species, we have to place the interesting Acleonce and, then, to decicle, from 

 what simpler form that curious growth is nearest to be derived. 



The great changes of the zooecia, produced by their calcification, make it very 

 difficult, in broken or worn fragments, to recognize this species. The most common 

 appearance is that of the rhomboidal zooecia, limited by a marginal furrow, with a de- 

 pressed, ovate area on their front side, which encloses the apparently reniform aperture, 

 that is encroached upon, proximally, by the raised tip of the median avicularium. The 

 Porinidan character of such a constitution, particularly as the median pore often is 

 missing, only will be understood in comparing it with the youngest zooecia in more 

 complete colonies. There, the elongated, almost cylindrical zooecia present their prim- 

 ary aperture of a semicircular shape, placed in a level with the plainly convex 

 front-side, which is perforated by the rounded median pore. The marginal furrows 

 are soon filled up by a calcification reticulated by pores. The distal part, with the 

 mouth of the zooecia, then, is raised, at the same time as the median avicularium is 

 developed between the mouth and the median pore. Now the front side, in its further 

 calcification, has produced one granulated ridge, running around the mouth, embracing 

 the median pore and avicularium, from both sides converging to the middle of the 

 front, whence it runs straight to the proximal end of the zooecion. In its thickening, 

 then, this ridge becomes the rounded wall around the above-named depressed area. 

 Proximally of this area, a new avicularium is developed, with its tip pointing down- 

 wards the stem (proximally) but otherwise retaining the same shape as the above-named 

 one. Then, in the overgrown and worn condition, particularly in the lower parts of 

 the stem, the species gets a totally different and very perplexing appearance, as if it 

 were composed of pyriform or, sometimes, rectangular zooecia, limited by a furrow, 

 with an ovate aperture (the rest of the area) and, below this, a rounded hole. which 



*) Esehara sulcata, Ann. d. Se. nat., ser. 2, vol. VI, p. 47, tab. V, fig. 2. 

 2 ) Esehara decussata, Cat. Brit. Mus., Polyz., p. 91, tab. CVII, figs. 4 — 6. 

 Of course that species is different from Esch. decussata, M. Edw. 



