106 Rev. T. Hincks on Pohjzoa 



to estimate tlieir precise significance. The mouth in C. ovata, 

 as I have seen it, is orbicular, slightly compressed or flattened 

 below ; in C. plicata it is decidedly subtriangular, and the 

 lower margin runs to a point. This is an important structural 

 distinction, the specific value of which we are certainly not 

 justified in rejecting without much fuller evidence respecting 

 transitional forms than we now possess. It is of course 

 eminently undesirable that species should be multiplied on 

 trifling pretexts ; it is equally undesirable that well-differen- 

 tiated and tolerably stable forms should be confounded. 



21. Cellepora plicata^ Smitt. (PI. XI. figs. 3 & 4.) 



Iceland, 100 fathoms. 



[Spitzbergen, 2-60 fathoms, very common {Smitt) ; Green- 

 land (German Polar Expedition) ; Godhavn Harbour, Disco, 

 5-20 fathoms {Xorman, 'Valorous' dredgings).] 



In this species the cells are ovate, somewhat depressed ; 

 surface smooth and glistening, sometimes traversed by ribs ra- 

 diating from the circumference ; mouth subtriangular, slightly 

 arched above, the sides running to a point in front, so as to 

 form an acute angle ; peristome thin and slightly raised at 

 the sides ; on one side a prominent mucro, bearing a large 

 elongate-oval avicularium, with rounded mandible, looking 

 obliquely sideways. Oooecium semicircular, smooth, punc- 

 tured in front. Allied to the preceding, but, I think, distinct. 

 A very salient character is the great length of the oval avicu- 

 larian opening. 



Genus ESCHARA, Ray. 



22. Eschar a pavo7ieUa, Alder. 



A single specimen was met with. 



[Spitzbergen, in 20-60 fathoms, not rare ( Torell and Swedish 

 Expedition) ; Finmark, in 20 fathoms {Goes and 21almgren). 

 Not yet found in Southern Scandinavia {Smitt). England, 

 north-eastern coast.] 



Genus Myriozoum, Donati. 



{Leieschara, Sars.) 



23. Myriozoum coarctatum^ Sars. 



Iceland, 100 fathoms. 



[Spitzbergen, in 19-80 fathoms (Swedish Expedition); Nor- 

 way {Strom, Sars, &c.).] 



24. Myriozoum, suhgracile, D'Orbigny. 



Iceland, 100 fathoms. 



[Spitzbergen, 19-80 fathoms, common (Swedish Expedi- 



