86 Rev. T. Hincks's Contributions towards 



occupied by the single prominent boss. This is somewhat 

 truncate above, and has a semicircular or wedge-shaped out- 

 line below. 



Membranipora delicatula, Busk. (PI. XI. fig. 1.) 



Biflustra delicatula, Busk, Crap: Polyzoa, p. 72, pi. i. figs. 1, 2. 

 ? Biflustra denticulata, Smitt, Floridan Bryozoa, pt. ii. p. 18, pi. iv. figs. 

 89-91 (not Membranipora denticulata, Busk). 



Zooscia quincuncial, quadrangular (the upper angles often 

 rounded), sometimes elongate, sometimes short and broad, 

 margins granulated transversely, about a quarter of the area 

 below occupied by a delicate lamina, finely granular, which 

 bears on its upper margin a projecting lobe or denticle (fre- 

 quently absent) set with minute spines or prickles, lamina 

 sometimes carried upwards to a slight extent along the inner 

 edge of the area, which occasionally bears a few denticulate 

 processes ; aperture ovate or elliptical, more or less fre- 

 quently a low blunt knob at each of the upper angles, some- 

 times only a single knob, often none. Avicularia none. 

 Ocecium (?) . 



Loc. Florida, incrusting weed [Miss Jelly). 



Range. Crag ; Australia ; ? Manilla ; Florida. 



This seems to be the Biflustra delicatula of Busk (an Aus- 

 tralian and Crag species), although, in some points, the two 

 differ ; and on this account I have given a description and 

 figure of the Floridan form. The latter is simply incrusting, 

 whereas the former is erect and foliaceous ; but this is not a 

 point of any significance, as the two states commonly enter 

 into the same life-history. Busk makes no mention of the 

 nodules ; but they are often absent ; nor of the denticles, which 

 in the fossil would probably not survive, and are frequently 

 wanting in the Floridan specimens. The transverse granu- 

 lation, too, on the border of the cells is much more marked, 

 as represented in Busk's figure, than in the latter. But all 

 these differences amount to little, and there can be no doubt 

 of the identity of the two forms. I am also inclined to think 

 that the Floridan species described and figured by Prof. Smitt 

 under the name of Biflustra denticulata * is the same thing. 

 It is true he does not mention the " serrated denticle " on the 

 edge of the lamina ; but though, when present, it is a very 

 striking feature, it is often undeveloped or very partially 

 developed, and I have seen large tracts of the crust in which 

 scarcely one was to be found. The figures, too, do show a 



* This must be accounted quite distinct from Busk's Membranipora 

 denticulata, a Mazatlau form, described in Carpenter's ' Catalogue of 

 Mazatlau Mollusca in the British Museum' (1855-57), p. 1. 



