1881.] THE SURVEY OF H.M.S. 'ALERT.' 59 



ginal portion and a suddenly rising median convex ridge, which only 

 occupies about one third of the total breadth of the lobe. A clear 

 space of about the breadth of a single cell is left down the middle 

 of the lobes ; and on each side of it are ranged the regular, outwardly 

 and forwardly diverging transverse lines of cells. These lines are 

 slightly but constantly subalternate, the line on the one side being 

 slightly in advance of or behind the corresponding one on the 

 other. The transverse lines on each side have from three to five 

 cells on the ridge and one or two on the horizontal lamina. The 

 cells project by a long perpendicular portion ; they are subopaque 

 and white, the surface faintly marked with rings of growth ; the 

 punctures are small and numerous and not prominent. The cells on 

 the ridge are variously united together, either three or two together, 

 but occasionally quite distinct ; those on the lamina are distinct 

 from those of the ridge, and from each other. In the case of the 

 united cells the uniting substance connects them generally from their 

 mouths downwards. The transverse series of cells are unheriid, and 

 present no such trifoliate outline as is given by d'Orbigny's figures 

 2 and 3, from which the present species also diverges by having a 

 distinct median line devoid of cells, as described above. A short 

 trumpet-shaped opening, observed near the end of a lobe, and 

 somewhat flattened, its long diameter being about twice that of 

 an ordinary cell, appears to represent the ooecial opening. The ends 

 of the lobes are not expanded as in T. Jlabellaris (Bask). 



This species does not correspond closely with d'Orbigny's figures; 

 but the chief diiference is the linear, not trifoliate arrangement of the 

 triple groups of cells. 



Hab. Elizabeth Island, G fathoms, on Fucus, with Tuhulipora 

 serpens, SchizoporcUa hyalina, and one or two other species of 

 Tubulipora, &c. 



TuBULiPORA DicHOTOMA, d'Orbigny. var. nov. serialis. (Plate 

 VI. fig. 10.) 



Criserpia dichotoma, d'Orbigny, pars, Voy. Amer. m6rid., Zooph. 

 p. 19, pi. ix. figs. 7-10. 



Tubulipora dichotomUy Busk, Cat. Polyz. Brit. Mus. iii. p. 27. 



Tubulipora oryanizans, Busk, Phil. Trans, clxviii. p. 193, pi. x. 

 figs. 20-25 (pars ?). 



Colony convex, elongated, dichotomously branched or incipiently 

 symmetrically bifid; lobes rising from base with hardly any lateral 

 lamina ; cells extending across top of ridge, arranged in more or less 

 distinct transverse rows, cells distinct (rarely two may be seen joined) 

 from one another. Surface of colony subopaque, white, thickly 

 covered with minute punctures surrounded by salient rims, the cells 

 less thickly covered by similar punctures. Cells moderately thin, 

 curving suddenly upward so as to stand almost perpendiculsr, free 

 for a distance of from 3 to 5 diameters ; opaque white, of moderate 

 diameter, faintly marked by concentric rings. Ends of lobes more 

 or less expanded and often swollen ; at this part the tubes lose 

 most of their regular radiate arrangement, 



