222 Rev. T. Hincka on the 



of the cell-wall immediately below the oritice is elevated, 

 and the central portion rises into the very prominent mucro ; 

 in the piesent form the front surface is almost uniform 

 throughout. The lateral aviculiferous processes, wliicli form 

 so remarkable a feature of the variety, are placed one on each 

 side of the orifice at the very top of the cell. They curve 

 inward a little above, and the avicularium is situated just 

 below the top on the inner face. In the var. bicornis [Le- 

 pralia hicornis^ Busk) there is a cylindrical process on each 

 side of tlie orifice, bearing an avicularium on the apex ; but 

 this would hardly be a correct description of the analogous 

 processes on the present form. In the var. tridens (Busk) 

 two processes are developed in a line with the central mucro ; 

 in both these cases, however, the general characters are those 

 of the normal P. Skenei. 



On the whole, I think, this form must be regarded as a 

 very remarkable variety of that species. Amongst the par- 

 tially developed cells on the crustaceous base of the latter 

 the mucro is undeveloped, and occasionally a pair of lateral 

 processes may be met with which closely resemble those of 

 the form lylana. The ooecium, which has some peculiarities, 

 seems to be alike in both. At the same time the amount of 

 divergence from the ordinary type of the species and the 

 change in external aspect which accompanies it are certainly 

 exceptional. 



In my ' History of British Polyzoa ' P. Skenei is ranked in 

 the genus Pahnicellaria^ Alder ; but I am now convinced 

 that its true affinity is with Porella. 



Loc. Gulf of St. Lawrence, Trinity Bay, 96 fath. 



Porella elegantula, D'Orbigny. (PI. XV. figs. 5.) 



Eschara elegantula, D'Orb. Pal. Frau9. Terr. Cret. v. p. 102 ; Packard, 



SoLitlieru Labradt)! Auimals, Canad. Nat. & Geol. viii. (186-3) ; 



Smitt, Kritisk Ftirteckn., OEfvers. K. V^etensk.-Akad. Forhandl. 18G7, 



p. 24 ; Dawsou, J. W., Postpliocene Geol. Canada, 1872, Cauad. Nat. 



n. s., vi. ; Busk, North Polar Poljzoa, Journ. Linu. See. xv. 1880; 



id. Chall. Rep. pt. i. p. 141. 

 Eschara saccata, Busk, Pol. Norway and Finmark, Ann. & Mag. Nat. 



Hist. ser. 2, xviii. p. 3 ; Sars, M., Norsk. Pol. I860 (sep.). 

 Eschara glabra, Hiucks, Pol. Barents Sea, Ann. & Mag. Nat. Hist. 



October 1880. 

 Porella elegantula, Levinsen, Bryoz. f. Kara-Havet. Dijmpbna-Togtets 



zool.-botan. Udbytte, 1886. 

 Lepralia elegantula, Lorenz, Pol. v. Jan IMayen, 1886. 



I am inclined to agree with Levinsen in referring this 

 interesting species to the genus Porella. In essential struc- 

 ture it resembles the latter, but the resemblance is somewhat 



