4 o EXPEDITION ANTARCTIQUE BELGE 



Micropora brevissima sp. nov. 



(PI. II. figs. ya-c 



Zoarium incrusting. Zoœcia broadly ovate, with distinct raised margins, but there are 

 no latéral « knobs », surface minutely granular and punctate, an elongate foramen on each 

 side a little below the oral aperture ; the oral aperture is very wide and short, directed forwards 

 rather than upwards. One small triangular avicularium (683) above the orifice has been 

 found, but they are usually absent, though from Cape Horn they occur frequently. Ovicell 

 globular, raised, smooth or slightly granular, and the ovicelligerous zoœcia are the same size 

 as the other zoœcia. There are pore chambers round the zoœcia, about six latéral ones 

 on each side and one distal. There are two oral spines, only seen however on the terminal 

 zoœcia. 



This differs from M. coriacea Esper, in having the oral aperture very wide and short, 

 in the absence of « knobs », and of the projection on the ovicell, though a trace of this can 

 sometimes be seen. The mandibles, as prepared from Cape Horn material, are about double 

 the size of those of M. coriacea and of the same type although there are minor différences. 

 It much resembles M. perforata MacG., in shape and other respects, but the operculum is 

 wider and shorter, perhaps they should be considered varieties. 



In M. stcnostoma Busk the ovicelligerous zoœcia are much larger than the others, whereas 

 in M. coriacca and M. brevissima they are the same size. 



The Escharina peruviana d'Orb. is probably M . perforata MacG. 



Habitat. — Cape Horn, and apparently from New Zealaml. 



Exp. Antarct. Belge. 



N° 288 on stones, dry, Dredge I. Lat. 71 09' S.- Long. 89" i5' W. ; 460 met. ; -Uo.3 C. 

 N° s 591, 596, Tangles VII. Lat. 70^ 23' S.- Long. 82^47' W. ; 480 met. ; +0.8 C. 

 N os 61g, 683, Tangles VIII. Lat. 70 00' S.- Long. So" 48' V. ; 5oo ? met. ; +0.9 C. 

 N° 820, Tangles X. Lat. 70° i5' S.- Long. 84 06' \Y. ; 56g met. ; +0.8 C. 



The geographical distribution of Micropora would seem to be ('). 

 Northern : M . (Cellaria) borealis Busk ; M. coriacea Esp. 



Mediterranean : M. coriacea Esp., M. impressa Moll. 

 N. Atlantic : M. coriacea Esp. 



S. Atlantic : M. uncifera B., M. coriacea Esp. 



Australasian : M. uncifera B., M. impressa Moll. (A. W". W. coll.). 



M. elongata Hincks, M. perforata MacG. 

 S. Indian Océan : M. coriacea Esp. 

 N. Pacific : M. borealis B. 



S. Pacific : M. perforata Mac G., as peruviana d'Orb. 



S. American : M. uncifera B., M. brevissima nov. 



Antarctic : M. coriacea Esp., M. brevissima nov. 



(1) I hâve given similav geographical lists of Flustra (Jouni. Roy, M ici-. Soc, 1896, p. 286); of Mcmbranipora 

 (Journ. Liun. Soc. Zool., vol. XXVI, p. 664); of Cribrilina [Joiirn. Linn. Soc. Zool., vol. XXVIII, p. 64). Species 

 piinted in italics occur from a second région. 



