152 Rev. T. Ilincks on the 



indicates affinity ^vitll the Schizoporellidae. Should further 

 examination show that the orifice in Flustra soUda is dimor- 

 plious, as it is in many of the Cheilostomata, and that tlie two 

 forms wliidi 1 have described are referable to one species, it 

 will ])robably iind a ]>lace in the above family. Unfortunately 

 I liave only had immature fragments of the so-called " smaller 

 form," and though they have enabled me to asceitain with 

 accuracy the structure of its cell-mouth, they do not furnish 

 the means of determining with certainty the relation between 

 the two forms. 



A striking characteristic of F. solida is the epidermal 

 covering of a uniform greyish tint which invests the surface 

 of the zcoecia and occasionally of the ooecium also, though 

 this is more usually free and retains its silvery lustre. The 

 chitinous iibres which hold together the detached segments 

 of the zoarium and also give origin to the organs of attach- 

 ment are tubular extensions of the membranous covering of 

 the cell* (PI. VIII. fig. If). 



Mo7ioporella sfinullfera^ Hincks, var. (PI. VIII. fig. 3.) 



Miicronella spinidifcra, Hincks, "PolyzoaoftheSt. Lawrence," 'Annals,' 

 May 1889, p. 431, pi. xxi. fig. 3. 



This species was described and figured in the last part of 

 this series of papers ; but 1 have since met with a strongly 

 marked variety (PI. VIII. fig. 3), which should not be passed 

 without notice. 



Var. '[iraclara. — Zoacia much larger than in the common 

 form, more convex and deeply divided ; innnediately below 

 the orifice a large umbo, which frequently rises to a con- 

 siderable height ; oral denticle wanting. 



The large size of the cell, the suboral umbo, and the 

 absence of so distinctive a feature as the sjiinule on the lower 

 margin materially affect the general a])pearance of the 

 zoarium. 



1 have ranked this species in the genus Mucronelhi ; but on 

 reconsideration I am inclined to think that its affinities are 

 rather with Monoporella. 



Smitt has described and figured M. spinulifera f under the 

 name Du-copora cnicnta, identifying it Avith the Lepralt'a 

 cruenta^ Norman, from which it difl'crs essentially, lie had 



* See a paper by the author, '' On new Ilydroida and Polyzoa from 

 Barents Sen,"' * Annals ' for October 1^>80, p. '2i>'2. 



t " Kriti.^k Fiirtec-luiiii}: iifv. Skandinaviens Ilafs-Hivozoer," (ICfvci'sigt 

 alKond. \etentk.-Alvad. lorhandl. 1.^71. 



