HEXACTINELLIDA. 3 



A curious phenomenon remains to be noticed. On October 24th, 1903, Lieutenant 

 Armitage's sledge party found a dried macerated Hexactinellid Sponge and also tufts of 

 spicules being "blown about by the wind amongst the erratics on the ice." The 

 existence of recent Hexactinellid Sponges on the surface of the earth and brought there 

 by natural agencies is a very unusual occurrence ; for, generally, these Sponges live in 

 too deep water to be cast up by storms. In the present instance, probably the sea 

 bottom was scooped up by ice, and the material afterwards floated up on detached 

 masses of ice. Both the specimen and tufts of spicules belong to a new species, viz., 

 Aulorossella levis, common in shallow water up to 20 fathoms. 



Abbreviations and Explanations. 



(1) W.Q. means " Winter Quarters." 



(2) A Roman and an Arabic numeral in brackets mean number of plate and 

 figure ; thus (I. 6) means Plate I., fig. 6. 



OEDER HEXACTINELLIDA, F. E. Schulze. 



Sub-order Hexasterophora, F. E. Schulze. 



Family Rossellid^, F. E. Schulze. 



Sub-family Rossellin^, F. E. Schulze. 



Hyalascus, Ijima. 



Hyalascus hodgsoni. 

 (Plate III. fig. 1, and Plate IV. figs. 1 a-g.) 



Sponge an elongated, slightly flattened oval sac, broadest a little above the base, 

 with an oval orifice with thin, soft, felt-like, unarmed edge. 



Surface with a few small, pointed, tuft-like conuli ; with oxydiactin, and rarely 

 oxypentactin pleuralia. With rounded base provided with short scattered bundles of 

 basalia (probably forming a root-tuft in complete specimens). Gastral membrane 

 continuous (to the naked eye). Autodermalia hexactins, rarely pentactins ; hypodermalia 

 oxypentactins with smooth surface. Gastralia slender hexactins. Intermedia 

 holoxyhexasters,* hemioxyhexasters, rarely monoxyhexasters * ; discohexasters, and 

 microdiscohexasters. Colour (in spirit), pale buff ; consistence rather soft and flexible, 

 but firm enough for the walls to be self-supporting when out of spirit. 



Description of the specimen. The single specimen representing the new species 

 appears to be in an incomplete state, and has probably been denuded of many pleuralia, 



* The term monoxyhexaster is used for oxyhexasters in which all the secondary or terminal rays are single, 

 hemioxyhexasters (Ijima) being oxyhexasters in which only one, or some, but not all, of the terminal rays 

 are single, and holoxyhexasters oxyhexasters with all the primary rays ending in more than one terminal ray ; 

 similarly, the terms holodiscohexaster, hemidiscohexaster (Schulze), and monodiscohexaster explain themselves. 

 Prof. Ijima's view (4, p. 118, footnote) that the first kind of spicules, viz., monoxyhexasters, should be designated 

 "hexasters" and not "hexactins " (Schulze, 9, pp. 8-11) seems to me justifiable. Firstly, the axial canals are 

 confined to the basal portion of each ray (primary ray) and do not extend to the terminal portion (secondary ray). 

 I have examined numerous monoxyhexasters and some monodiscohexasters, and by using a 12-inch oil immersion 

 and by adjusting the light, I have invariably found that the axial canal comes to an abrupt end not far from the 



VOL. III. ^ H 



