240 ME. G. BUSK ON THE POLTZOA 



As the present collection affords only a single specimen of this 

 very interesting form, and that of small size as compared with 

 Crag specimens, it might fairly be allowed that the absence of 

 anastomoses was accidental, and consequent upon youth ; but 

 when I find that the same character was presented in specimens 

 examined by Professor Smitt, and which, according to his mea- 

 surements, appear to have had about the same dimensions as the 

 one collected by Capt. Feilden, I am much disposed to look upon 

 it as a very important differential character. I regarded it as 

 such in the case of the numerous fossil, mostly Cretaceous, forms 

 of Mesenteripora, and should be equally inclined to regard it as 

 distinctive between the existing Arctic species and that from the 

 Coralline Crag. Among other points of difference I would 

 mention : — 



1. The greater thinness of the Crag species and the much 

 greater size attained by the zoarium. 



2. The apparently thicker peristome, and (so far as can be 

 judged in fossil specimens that have been exposed perhaps to 

 attrition) the circumstance that the extremities of the zooecia 

 were not produced beyond the surface, or much less so than in 

 the recent form. 



G-enus Tubulipora. 



1. Tubttlipora ventricosa, Busk. 



Tubulipora ventricosa, Busk, Quart. Journ. Mic. Sc. iii. p. 256, pi. ii. 

 figs. 3 & 4 ; Brit. Mus. Cat. part iii. p. 26, pi. 32. fig 4 (same figure). 



Tubulipora (subgenus Proboscina) incrassata (var. , forma erecta), 

 Smitt, I. c. 1S66, p. 402, pi. v. fig. 4. 



Hab. Arctic Sea, Aug. 11, 1875, 13-15 fms. ( R. W. F.) ; 

 Greenland (on fucus) {Dr. Sutherland). 



I have omitted several synonyms given by Professor Smitt, not 

 feeling that any certainty can be attached to them. 



Captain Feilden's collection contains only a single specimen, 

 but this affords excellent characters. 



Suborder III. CTENOSTOMATA. 

 Fam. 1. Vesiculariid^. 

 Genus Farrella, Ehrenb. 



1. Farrella ?, n. sp. PI. XIII. fig. 9. 



Zooecia in opposite pairs at very distant intervals on a slender 

 tubular stem. The largest 0"-06 x 0"-013. 



