FL0E1DAN BRYOZOA. 27 



that type and with the marginal spines in the number of 11, uniformly distributed 

 on the whole margin. 



At the development of the ooecia, particularly in the higher degrees of calcifica- 

 tion, once x ) 1 have shown, how the margin of the ooecial aperture, in growing forth 

 över the front side of the zocecion, covers the zooecial aperture as well as a semicircu- 

 lar space, proximally of this, enclosing the lunate median pore. Now, on the Floridan 

 specimens we find that same process going on still further, in producing (fig. 129) a 

 transverse bridge över the thus formed secondary aperture. In the southern Atlantic, 

 at the Falkland-Islands, the Porellina diademata (Flustra diademata, Lmrx., in Quoy, 

 Gaim., Voy. de VUranie, ZooL, p. 609, pl. 89, figs. 3—6 = Lepralia personata, Busk, 

 Cat. Brit. Mus. Polyz., p. 74, pl. 90, figs. 2 — 4) represents another variety in the man- 

 ner of developing this secondary aperture. 



As to the generic name Porellina, it has been necessary to replace that name 

 instead of Porina, as I formerly used it, for that group of this family, which retains 

 the median pore in its lunate form, because the most typical species of Porina, by 

 D'Orbigny, have this pore rounded, as we will find to be the case more constantly in 

 the following species. 



As one example of a raised stem of the genus Porellina I may cite the Porellina 

 (Eschara) fiabellaris, (Busk) 2 ). 



Porina serrulata, n. sp. (Pl. V, figs. 116 — 125). 



Char.: Zooecia ovalia, elongata, frontem primariam pra?bent sparse porosam, apertu- 

 ram primariam semiellipticam (cujus låtit. = 0,09 — 0,1 mm. circ); porum 

 medianum pone aperturam prsebent rotundum; avicularia minima in media 

 longitudine praebent lateralia, transverse posita, mandibulo rotundato clausa. 

 Ocecia rotunda, postremo calcificatione colonias obducta, frontem prcebent 

 aperte rimatam, rima costis transversis, in linea media connatis, clausa. 

 Avicularia majora spathulata inter zooscia disponuntur (prassertim in mar- 

 gine bryozoarii erecti, ramosi, ramis planatis) magnitudinem fere zocecio- 

 rum tenent. 

 Hab.: Pourtales hane speciem Sertularise affixam e prof. 35 — 42 orgyarum ad 



Floridam cepit. 

 It is one of the most interesting Porince, because, in the front side of its ooecia 

 (fig. 122), it most strikingly remembers us of the construetion of the front side of the 

 zooecia of the Membraniporellce. This, also, when the ocecia are developed, will be its 

 best recollecting character, but otherwise, in wanting the ocecia, the great, spathulate 

 avicularia, in connexion with the Porinidan strueture of the- zooecia, will suffice for 

 recognizing it. Of the named avicularia, those who are placed in the margin of the 

 stem (fig. 123) often increase to a size almost equalling that of the zooecia. Then, 

 with their spathulate area, as they are placed upwards, a little obliquely outwards, in 



l ) Krit. Fört., 1. c. : p. 60, Anm., pl. XXIV, figs. 13 and 14. 

 "-) Cat. Brit. Mus., Polyz., p. 91, pl. CVII, figs. 7—10. 



