18 IDMONEID^. 



fibrilltited, granular, punctured ; mouths of zoooecia circular, level 

 with the surface, arranged in irregular quincunx ; peristome entire, 

 slightly thickened ; dorsal surface granular, irregularly sulcate, 

 densely punctured with unequal round pores ; oooecium unknown. 



Hab. Cape Capricorn, 15 fathoms ( Voy. Battlesnahe) ; Tierra del 

 Fuego, 53° S., 30 fathoms (C. Darwin). 



The Australian form is rather more robust than the Fuegian ; but 

 in essential characters the two appear to coincide. 



4. Hornera pectinata, Busk. 



Zoarium irregularly branched ; branches terete ; anterior surface 

 sparsely punctured and obscurely ridged, porcellaneous, dorsal 

 sparsely punctured ; mouths of zoooecia exsorted ; peristome pecti- 

 nate ; oooecia unknown. 



Hornera pectinata, Bk. Quad. Jount. Mic. Set. new ser. vol. i. p. 79, 

 pi. xxxiii. tigs. 4-0. 



Hab. Madeira (/. F. Johnson). 



b. Species with the ooa-cia anterior, either ivholli/ or in ;>«)•< ; surface in 

 front not Jilrillated or sulcate. 



5. Hornera violacea, Sars. (Plate XVIII. figs. 1-4.) 



Zoarium irregularly branched ; branches short, truncate ; zoooecia 

 distinct, immersed or in part free ; dorsal surface granular or very 

 finely striated with minute pores ; ovicells elongated, situated in the 

 axils of the branches, partly in front and partly behind, smooth and 

 finely punctate, with a thin median costa. 



Hornera violacea ( forma violacea), Smitt, I. c. p. 404, tab. vi. figs, tj- 

 9 ; Sars, Geol. og Zool. Jaytt. Reise Trondj. 1862, Nyt Mag. Nat. 

 Vicl. xii. p. 282. 



Pustulopora orcadensis, Bk. Q. J. Mic. Sc. (1860), viii. p. 214, pi. 39. 

 figs. 1, 2. 



Hab. Arctic Seas ; coast of Norway, Hammerfest (Sars). 



Yar. a. proboscina. (Plate XVIII. figs. 1, 3.) Oooecia in front, 

 suborbicular, umbilicate, finely punctate. 



Hornera violacea (forma proboscina), Sniitt, I. c. p. 404, pi. vi. figs. 

 2 &5. 



Zoarium irregularly branched ; branches lax and straggling ; 

 zoooecia tubular, distinct, elongated, in great part free ; anterior 

 surface without sulci, ridges, or punctures ; dorsal surface granular, 

 finely punctate ; oooecia anterior, suborbiciilar or elongate, situated 

 in the axils of the branches, partly in front and partly behind (Nor- 

 man) ; smooth, finely punctate, with a thin median costa. 



