52 Rev. T’. Hincks on the 
Smittia plicata, Smitt. 
Houston-Stewart Channel ; off Cumshewa, 20 fms. : not un- 
common. 
[Spitzbergen, Greenland, 100 fms., Godhavn Harbour, 
Disco. 
The form which I refer to Smitt’s Cellepora plicata differs 
slightly from the description and figures given by that author ; 
but in essential particulars, I believe, it agrees with them. 
In the specimens from the Queen Charlotte Islands the avicu- 
larium is well within the peristome, and there is little if any 
trace of the umbo, on which, according to Smitt, it is placed 
in his OC. plicata. This, however, may be due to the greater 
development of the peristome, by which the umbo may have 
been to a large extent concealed. The cells are often in- 
vested by a membranous epitheca. 
Smittia spathulifera, n. sp. (Pl. IV. fig. 3.) 
Zoecia large, ovate, quincuncially arranged, very mode- 
rately convex, bordered by delicate raised lines; surface 
covered with rather large round punctures, which, however, 
are in great measure concealed by the stout epitheca that 
clothes the zoarium; orifice arched above, lower margin 
straight and within it a large bifid tooth; peristome much 
raised (especially above) forming an elongate secondary orifice, 
produced below into a spout-like sinus, which is occupied by 
a spatulate aviculartum; mandible directed downwards. 
Ocecium large, immersed, closely united to the cell above ; 
surface roughened, punctured round the edge. Zoarium 
forming a brownish crust. 
Houston-Stewart Channel. 
Muvcrone.ia, Hincks. 
Mucronella ventricosa, Hassall. 
Virago Sound, in about 20 fms., on shells. 
[Britain, France (S.W.), Mediterranean, New Zealand, 
Bergen, Greenland, Nova Zembla, Kara Sea. ] 
Mucronella pavonella, Alder. 
Virago Sound. ; 
[St. Lawrence, Greenland, Nova Zembla, Spitzbergen, Fin- 
mark, off Jutland, Britain (north-east) .] 
Mucronella prelucida, n. sp. (Pl. IV. fig. 1.) 
Zeocia large, ovate, quincuncial, slightly convex, separated 
