1881.] THE SURVEY OF H. M.S. ' ALERT.' 57 



The erect portion of the cell appears to be obscurely annulated, 

 a very slight annular depression connecting the serially arranged 

 puncta. A somewhat injured dry specimen on indurated clav. 



Hab. Lat. 50^ 35' S., long. 66^ 31' W. (open sea off S.E. Pata- 

 gonia), 58 fathoms. 



LiCHENOPORA GRiGNONENSis, Busk. (Plate VI. fig. 2.) 



TubuUpora grignonensis, Milne-Edwards?, Mem, Tubulipores, 

 Ann. Sci. Nat. (2) viii. p. 333, pi. xiii. fig. 2. 



Discoporella grignonensis. Busk, Crag Polyzoa, p. llG, pi. xx. 

 fig. 4. 



Lichenopora, Defrance ; Hincks, Hist. Brit. Mar. Polyz. p. 471. 



Zoarium simple, closely adnate. Lamina very narrow, thin, almost 

 entirely occupied by ridges indicating rudimentary zocEcia. Zoa- 

 rium strongly convex from the centre to the lamina, circular in 

 outline. Zocecia partially arranged in radiating series (the series 

 generally interrupted by the occurrence of intermediate cells) around 

 a small central space ; orifices raised, considerably so near the centre ; 

 the entire front of the peristome wanting, posterior part horseshoe- 

 shaped, margin obscurely roughened ; sides faintly ridged longitu- 

 dinally, and bearing from three to about ten scattered delicate pointed 

 spines not exceeding half the diameter of the cell in length. Inter- 

 spaces between zocecia and the central area crossed by a network of 

 trabeculse, enclosing polygonal spaces with rounded angles ; those 

 between the zocecia vary in diameter from one half the breadth to the 

 same breadth, that of the orifices of the zocecia, those in the centre 

 varying from that diameter to twice its size, and partially tympanized 

 by a calcareous septum with a central perforation ; also from the 

 points of junction of the trabeculse which form them projects oc- 

 casionally a slender spine like those on the walls of the zocecia. 

 Ooecial orifice slightly raised, being surrounded by a thin, narrow, 

 forwardly sloping rim perforated by a single circle of about six 

 small punctures ; diameter of opening about twice that of a zooecium ; 

 margin finely dentate. 



Hub. Sandy Point, 9-10 fathoms, on piece of a Selachian's egg. 



Four colonies occur, representing three different stages, the latest 

 with fifty-thi-ee or more well-developed zocecial openings, the 

 earliest with only about a dozen openings, scarcely raised above the 

 general surface, the lamina being about twice as broad as in the 

 oldest specimen. In this young specimen, too, the cancelli have 

 hardly appeared, the surface between the cells bearing only an occa- 

 sional puncture. The development of the spines can be traced from 

 a stage in which they are mere short blunt tubercles to that in which 

 they have the adult proportions. It is also interesting to note that 

 in the same stage (the middle one of the three here represented), in 

 which the zocecia are 2 millims. in greatest diameter, the longitudinal 

 ridges, so indistinct in the oldest specimen, project boldly from the 

 zocecial wall and sometimes form prominent crenations on the margin. 

 The three young colonies have a somewhat oval outline ; the older 



