FLORIDAN BRYOZOA. 59 



The above describecl formation of a median denticle of the zooecial aperture 

 which more| constantly will be found in the following species, with the genus Escha- 

 rella conjoins a new Floridan species. 



Escharella bisinuata (Pl. XII, fig. 229). 



s Char.: Zooecia rectangularia, fronte fere plana, porösa, linea calcarea elevata dis- 

 juncta, apertnram rotundate-quadrangularem (cujns latitudo = 0,26 mm.) calcificatione 

 leviter torquatam, margine proximali recto bisinuatam praebent, aviculario laterali sat 

 magno (cujus- låtit. =0,ii mm.) naviculari (elongato, decumbente) muniuntur, in pariete 

 posteriori foramine rotundo aperiuntur. Oo3cia rotunda poris minutissimis perforantur. 



Hab.: Hane speciem, Hemescharce (au ett.) formam, e proff. 9 et 19 orgyarum ce- 

 pit Pourtales. 



Through the size of its zooecia, amounting to about 1 mm., and through their plain, 

 rectangular form, this species, among the Floridan Escharines, already for the naked 

 eye easily is recognized. The eolonies, of a whitish calcareous hue, are growing in the 

 Hemescharan manner. At the back side, the zooecia present a rounded hole, Avith a 

 strengthened, well defined margin. The zooecial apertures, rounded in their distal part, 

 are a little constricted at the articulation of the operculum, whereby the proximal 

 corners, otherwise rectangular, are rounded into the form of sinuses. The proximal 

 margin of these apertures, when complete, is straight, with two rounded sinuses, se- 

 parated by a median denticle. Around the zooecial aperture, a marginal space, usu- 

 ally thickened, of a little harder calcification, is marked out from the other front side 

 of the zooecion, on which the pores, of a more or less regular, quincuncial arrange- 

 ment, are very conspicuous. The avicnlaria, of a navicular shape, are placed laterally, 

 one on each zooecion, usually with the distal half of their aperture in breadth with 

 the zooecial aperture, though in this respect, as commonly, they can be varying. The 

 line of articulation of their mandible, usually, is strengthened by a calcareous trans- 

 verse rib. The ooecia are uniformly rounded, finely prickled by minute pores, which, 

 in the harder calcifications, scarcely are perceptible. 



After the PouRTALES-collections to judge, this species seems not to be of a very 

 frequent occurrence in the Floridan sea, though he has sent it in well-developed spe- 

 cimens, the one growing as a crust on a Nullipora, the other in fragments of a raised 

 Hemescharan growth. 



s 1 



Escharella Jacotini 1 ) (Pl. X, figs. 199 and 200). 



Of this well-known species, Pourtales has taken some eolonies, in varying states 

 of development, from 13 — 44 fathoms, growing on Nullipora, Steginoporella and Porina. 

 The one of these eolonies (fig. 199) is a very young one, with the zooecia of the al- 

 most typical constitution, although it still wants the avicularia. Another colony, how- 

 ever (fig. 200), of greater size, has grown out into the constitution of that variety, 



') Synonyma vide in Ofvers. Vet. Akad. Pörh., 1867, Bih., p. 11. 



