ASTRORHIZIDAE — IRIDIA ; HALIPHYSEMA. 



19 



Isles. There are, therefore, one or more tropical species of the 

 form described here in both the Indo-Pacific and the West Indian 

 regions. In general it may be said that the faunas of these two 

 regions are much more nearly allied than are either of them to the 

 fauna of the British Isles. 



In the living specimens which I had under observation it was 

 noted that the pseudopodia followed out the spicules of the "capit- 

 ulum" and then off into the water, while others came out appar- 

 ently through interstices of the cylindrical part. The pseudopodia 

 were all very fine and clear, with few branches and little anastomos- 

 ing, as shown by Moebius in his figures. The spicules of the 

 "capitulum" were variously placed, some with the point of the 

 spicules out, others with a rounded end outward. These spicules 

 were usually entire and more or less covered by a film of foreign 

 material, evidently brought in by the contracting of the pseudopodia. 

 In the specimen figured (fig. 1), an appendage of a copepod had been 

 inserted among the spicules and extended out to several times the 

 length of the spicules. Moebius (loc. cit., pi. 1, fig. 4) shows a 

 specimen with a pecuUar body standing up above the spicules. 



In this connection it seems fitting to call attention 

 to the observations of Heron-Allen and Earland 

 on Marsipella cylindrica H. B. Brady (Journ. Roy. 

 Micr. Soc, 1912, p. 388). They show there that a 

 specimen from the Faroe Channel found by Earland 

 had a capitular end very similar to that figured here. 

 It may be questioned whether that specimen is really 

 "the perfect organism" referred to by the authors, 

 or whether it may not have originally had a base 

 and been really a species of Haliphysema. In short, 

 is not Marsipella cylindrica H. B. Brady really 

 Haliphysema cylindrica (H. B. Brady)? Instead of 

 modifying Norman's original description of Marsi- 

 pella to include the capitular head and cylindrical 

 body, it seems very probable that a base will later 

 be found for the Marsipella cylindrica. The type 

 species of Marsipella, M. elongata Norman, is evi- 

 dently a very different organism from M. cylindrica, 

 the fusiform shape of M. elongata and the tapering 

 necks at either end from a body composed largely 

 of sand-grains making it seem in its general relations 

 very different from that found by Earland. 



FiQ. 1. — Haliphysema advena, new species. X25. Showing general out- 

 line of specimen, a broad basal portion, slender cylindrical column, and 

 capitular "head." The long, projecting body is an appendage of a 

 copepod which was used among the usual sponge-epiculea. 



