1. Sigmaspura. ; 
bo 
Spirula ; 
Spinispira ; 
4. Microspira; 
Ge 
5. Sterrospira ; 
B-Spuravons. 
1. Sigma; 
det Chela 
3. Dianceistra; 
References. 
BOWERBANK in: Philos. Trans. R. Soe. Londen, CXLVIII. 
Scumipt in: Spongién Adriat. Meeres. 
BowrErBaNk in: Monogr. Brit. Spong. I. 
Körtaker in: Icones histiol. I. 
Scumipt in: Grundz. Spong. Atl. Geb. 
Gray in: Ann. & Mag. (4, XII. 
CARTER in: Ann. & Mag. (4) XVI. 
CARTER in: Ann. & Mag. (5) III. 
Vosmaer in: Tijdschr. Ned. Dierk. Ver. V. 
Vosmaer in: Bronn’s Klassen u. Ordn.-Porifera. 
LeviNseN in: Dympha-Togtets Zool. Udbytte. 
SoLLAS in: Scient. Proc. R. Dublin Soe. ; 
Riptey & Denny in: Challenger Rep. Zool. XX. 
Sorras in: Challenger Rep. Zool. XXY. 
Senurze & LENDENFELD in: Abh. K. Pr. Akad.Wiss. Berlin 1889. 
LENDENFELD in: Abh. Senekenb. Naturf. Ges. XVI. 
1891(@) Kerner in: Zeitschr. Wiss. Zool. LIL. 
1894(d) LenprenreLp in: Biol. Centralbl. XIV, 
1858 
1862 
1864 
1864 
1870 
1873 
1875 
1879(«) 
1881 (a) 
1884 
1886 
1886 
1887 
1888 
1889 
1890 
( 143 ) 
smooth a-spiraxon of no more than 1'/, 
revolution. 
smooth a@-spiraxon of at least 1°/, revolution. 
spined «-spiraxon. 
very minute, smooth or spined «-spiraxon: 
it unites the characters of 1 and 3 dimi- 
nutively, and frequently forms transitions 
and reductions. 
the young stages are spinispirae, from which 
develop by secondary soldering together of 
the spines the adult forms. 
The axis is a line, drawn on an elliptic 
cylinder; the pitch is always small; always 
less than one revolution. Hereto belong: 
smooth #-spiraxon. 
the young stages are sigmata; in course of 
development very complicated siliceous pro- 
cesses grow out; we distinguish two sorts, 
viz. isochelae and anisochelae. 
the young stages are (probably) sigmata 
from which develop the adult ones by 
outgrowth of siliceous processes. 
