78 "TERRA NOVA' EXPEDITION. 



ill the size of tlie internal cavity, it represents a form midway l)et\veen iS. albida 

 and CritUonina qranum.. Goes, and it liecomes a question whether Goes's generic 

 name should not l)e abandoned in favour of Schulze"s earlier creation. 



DENDROXINA, nov. gen. 



Test sessile or free, unseptate, built of fine mud. sand-grams and sponge- 

 spicules, agglutinated with varying proportions of cement and furnished with an 

 internal or external chitinous membrane. 



Initial portion of sessile specimens either a depressed amoebiforni liasal pad, 

 with rainifving passages converging to a central cavity, or a more or less turgid 

 basal chamber, with simple or labyrinthic cavity. From the basal pad or chamber 

 rise one or more tubular outgrowths, simple or l)ranching. diminishing in diameter 

 towards the terminal apertures. 



Tn free-growing specimens the basal portion is l)ulbous with entire or 

 labyrinthic cavity, often of large size, from which arise one or more tubular 

 outgrowths developing as in the sessile form. 



Verv fragile in the drv condition, but ]n()bal)Iv more or less flexible in the living 

 state. 



The ■" Terra Nova "" material furnishes representatives of this new genus of 

 Astrorhizidae, which forms a connecting link between Masonella. Brady, and 

 Dendrophrya, Strethill Wright. Its affinities with the former are shown Ijy the 

 labyrinthic structure of the basal pad. and with the latter by its unseptate 

 tubular extensions and the occurrence of specimens showing only rudimentary 

 la1)yrinthic structure. 



Two distinct species occur in the New Zealand area, wliidi are replaced in 

 the Antarctic by two varieties of simpler structure, and less striking develop- 

 ment. We have fragments of what appears to be a similar organism from 

 Mauritius, and the genus may prove eventually to have a wide distribution. 



74. Dendronina arborescens, sp. nov. PI. II. figs. 10-12, 14-18. 



Stations 2, 3, 4. 6. 



Organism usually sessile, but sometimes free ; imseptate ; arborescent ; com- 

 mencing m the sessile form with a basal pad of irregular shape, attached to 

 stones, sponges and other bodies, and, in the free form, with a more or less l)un)ous 

 thin-walled chamber of large dimensions. From the basal pad or Inilb arise one 

 or more hollow unseptate and thick-walled tiunks of varymg lengths and pro- 

 portions, constructed of fine grey mud, sand, and sponge-spicules with a consider- 

 able proportion of cement. The sponge-spicules are regularly laid with their long 

 axes parallel to the line of growth of the trunk, which furcates at irregular 

 intervals into branches of diminishing size. Surface-walls of basal pad, trunk and 

 jiranches smooth, either matt or exhibiting, a glaze due to the presence of a 



