184 



GEODIA LOPHOTllIAENA. 



The niesoprotriaenes (Plate 47, fig. 34) have a fairly straight rhabdome, 

 about 1.3 mm. long and, at the cladome, 4-9 p. thick; in its thickest part, near 

 the middle of its length, it measures 7-11 pt in transverse diameter. The cladcs 

 are fairly equal, slender, conical, pointed, and curved, concave to the epirhabd. 

 Their chords are 44-80 /x long and enclose angles of 32-41°, on an average 35°, 

 with the axis of the epirhabd. The epirhabd is straight, conical, and 38-60 fx 

 long. 



The large anatriaenes (Plate 47, figs. 35, 36). I found no large anatriaenes 

 with the rhabdome intact, so that I am unable to give its length. At the cla- 

 dome the rhabdome is 8-13 fi thick. The cladome is without apical protuber- 

 ance. The clades are fairly equal, slender, conical, and sharp pointed. Their 

 proximal parts are quite strongly curved, concave to the rhabdome, their distal 

 parts straight. The chords of the clades are 60-85 /x long and enclose angles 

 of 41-50°, on an average 44.5°, with the axis of the rhabdome. 



The minute dermal anatriaenes have a fairly straight rhabdome, 170-210 /j. 

 long. At the cladome the rhabdome is 1-3 /x, at its thickest point, near the 

 middle, 2-4 p thick. The acladomal end is pointed. The fairly equal clades 

 are conical, blunt, and not very strongly curved, concave to the rhabdome. 

 Their chords are 4-9 ji long and enclose angles of 49-67°, on an average 56°, 

 with the axis of the rhabdome. 



The large oxyasters (Plate 48, figs. 1, 2, 11, 12b, 16-18, 21, 32b) are either 

 without a central thickening or have a small centrum up to 4 p., that is, one eighth 

 to one tenth of the whole aster in diameter. There are from four to eleven, 

 rather regularly distributed and usually equal, straight, conical, sharp pointed 

 rays. The rays are perfectly smooth, 8-22 p long and, at the base, 1-2.2 p thick. 

 Very rarely one or two of the rays are reduced in length and terminally rounded. 

 The total diameter of the aster is 15-41 p. A correlation (inverse proportion) 

 between ray-number and total diameter is indicated, the oxyasters with from 

 four to seven rays being 23-41 p, those with from eight to eleven rays only 

 15-30 p, in diameter. 



The sphaerasters (Plate 48, figs. 10b, 12a, 13-15, 19, 20, 22-26, 32a) have a 

 centrum 2-8 p, from one sixth to nearly one half of the whole aster, in diameter. 

 From this from seven to twenty-two, rarely as many as twenty-eight, quite 

 regularly distributed rays arise radially. The rays are usually cylindroconical, 

 and attenuated more (Plate 48, figs. 23-26) or less (Plate 48, figs. 20, 22, 23) 

 towards their ends, the end itself being truncate or rounded and crowned by a 

 terminal spine; much more rarely the rays are conical and pointed (Plate 48, 



