GEODIA LOPHOTRIAENA. 



185 



fig. 19). The rays are as a rule covered with spines which increase in size 

 towards the end of the ray, the largest often forming a verticil at or just below 

 its end; smooth rays (Plate 48, fig. 19) are exceedingly rare. The rays are, 

 without the centrum, 3-8 /i long, and, at the base, 0.8-2.4 /t thick. The diam- 

 eter of the whole aster is 7-22 //. The few-rayed of these asters are larger, 

 have smaller centra, and more slender rays than the many-rayed. In the cen- 

 trifugal spicule-preparations I have found a few smaller strongylosphaerasters, 

 the total diameter of which was only 4.5 p.. These rare asters may be young 

 forms of the ones described above, or foreign. 



The sterrasters (Plate 47, fig. 23; Plate 48, figs. 27-31, 33, 34) are sphaeroids 

 or relatively very broad flattened ellipsoids. They usually measure 30-45 fj. in 

 length, 30-44 /x in breadth, and 27-35 n in thickness. Often the sterraster has, 

 when viewed from above (with the umbilicus in the centre), a regularly circular 

 outline, but even when this outline is oval the differences between the two axes 

 is quite insignificant. The average proportion of length to breadth to thickness 

 of the sterrasters is 100 : 99 : 87. In the spicule-preparations I found, besides 

 these sterrasters, a few larger ones, similar in shape, but 57-58 /j. long (Plate 48, 

 fig. 28). These may, very likely, be foreign spicules. 



The umbilicus is 6-9 /t broad and about 6 fx deep. The rays away from it 

 are about 2 fi thick and have circular or polygonal transverse sections (Plate 

 48, figs. 33, 34) ; the rays surrounding the umbilicus are 3-5 /.i thick and have 

 transverse sections more or less elongated in a direction radial to the umbilicus 

 (Plate 48, figs. 30, 31). The ends of the rays bear from seven to eleven small 

 spines. From one to three of these arise from the terminal face, the others are 

 vertical to the axis of the ray and form a verticil round its end. 



The seven specimens of this sponge are labeled 6312. In the list of the 

 specimens sent, 6312 does not occur, nor, except 6311, any number near it. There 

 is therefore some probability that 6312 should be 6311, the locality of which is 

 New Zealand, so that New Zealand may be the habitat of these sponges. 



Although I have not been able to make out quite clearly the nature of the 

 entrances and exits of the canal-system, I think there can be little doubt that 

 both are cribriporal. For this reason and because the skeleton is distinctly 

 geodine in character, I place these sponges in Geodia. The sponges described 

 by Kieschnick * as Cydonium sphaeroides, by Lindgren ^ as Geodia arripiens, and 



' 0. Kieschnick. Silicispongiae von Tcrnate. Zool. anz., 1896, 19, p. 529. 



^ N. G. Lindgren. Beitrag zur kenntniss der spongienfautia des Malayisehen Archipels. Zool. 

 jahrb. Syst., 1898, 11, p. 346, plate 18, figs. 10, 18, plate 20, fig. 5. 



