GEODIA ATAXASTRA. 



95 



DIMENSIONS AND CHARACTERS OF THE SPICULES OF THE TWO VARIETIES OF 



GEODIA ATAXASTRA. 



Spicules. 



var. angustana. 



var. latana. 



Large choanosoinal 

 rhabds 



chiefly amphiox, amphistrongyles 

 and styles rare; 1.2-2.8, mostly 

 L6-1.8 mm. long and 17-43, mostly 

 22-38 /( thick. 



chiefly amphiox, but amphistron- 

 gyles and styles relatively much more 

 frequent; 0.6-1.9, mostly 1.2-1.6 

 mm. long, and 12-37 /< thick. 



Minute dermal rhabds 



nearly all amphiox, styles exceed- 

 ingly rare; 120-200, mostly 160- 

 200 /( long, and 3-5 /< thick. 



chiefly amphiox, but also a fair num- 

 ber of styles; 145-215 /( long, and 

 4-7 /( thick. 



Orthoplagiotriaenes 



rhabdome 1.6-2.3, mostly 1.9-2.2 

 mm. long, and at cladome 29-70, 

 mostly 40-60 /< thick; clades 170- 

 290, mostly 230-270 /< long; clade- 

 angle 85-116°, average 100.3°. 



rhabdome 1..3-1.7, mostly 1.5-1.6 

 mm. long, and, at cladome, 30-45, 

 mostly 30-40 /( thick; clades 130- 

 220 /( long; clade-angle 95-111°, 

 average 101°. 



Mesoproclades (nearly 

 all are triaene) 



rhabdome 1.6-3.4, mostly 2.1-2.8 

 mm. long, and, at cladome, 9-20 /; 

 thick; (longest) clades 44-80 /< long; 

 clade-epirhabd angles 33-48°, average 

 41.3°; epirhabd 33-73, mostly 40-60 

 /( long. 



rhabdome 2-2.4 mm. long, and, at 

 cladome, 7-13 /i thick; longest clades 

 25-58, mostly 32-50 long; clade- 

 epirhabd angle 25-58°, average 43.6°; 

 epirhabd 28-50, mostly 34-47 /< long. 



Large anatriaenes 



rhabdome 2.1-3.1 mm. long; at 

 cladome, 3-10 /i thick; (longest) clades 

 17-68, mostly 30-65 /t long; clade- 

 angles 20-42°, average 34°. 



rhabdome 2-2.8 mm. long, and, at 

 cUnlome 7-12 /( thick; (longest) clades 

 30-55 /( long; clade-angles 41-55°, 

 average 47°. 



Minute dermal ana- 

 elades 



rhabdome 190-340 n long; at clad- 

 ome, 0.5-2 /( thick; clades 2-6 /< long; 

 clade-angles 33-57°, average 47.6°. 



not ob.served. 



Large oxyasters 



two-rayed 40-50, three- to seven- 

 rayed 21-40, eight- to ten-rayed 15- 

 28 /( in diameter. 



three- to seven-rayed 17-28, eight- 

 to eleven-rayed 15-21. 5, u in diameter. 



Oxysphaerasters with 

 slender, spined rays 



8-13 /( in diameter. 



10-14.4 /( in diameter. 



Oxysphaerasters with 

 stout, smooth rays 



not observed. 



13 /( in diameter, rare. 



Small strongylosphaer- 

 asters 



2.6-6 /( in diameter. 



3-6.4 /t in diameter. 



Ataxasters 



4-7 /( in diameter. 



5.3-8.3 /( in diameter. 



Aeanthtylasters 



with ten to fourteen rays, 8-16 /< in 

 diameter, very rare. 



with fovu' to nine rays, 10-14.5 /( in 

 diameter. 



Irregular asters (sterr- 

 aster-derivates) 



not observed. 



21-50 /! in diameter. 



Sterrasters 



65-78 /( long, 

 58-67 /t broad, 

 47-57 /( thick. 



55-65 /I long, 

 50-60 /( broad, 

 47-50 /< thick. 



