SPONOIIDA. 
481 
(3) Sycones. Gastric wall very regularly permeated by straight 
and unramified canals i = Granti<s, Bovverb. ; Sycones, Lieberk.). 
Types Grantia (Sycon) ciliata and G. coinpressa : nearest the 
corals. It is plain that the Ascones form the main stem of the 
calcareous sponges, from which the other two groups diverge in 
opposite directions. The older systems of classification were 
not based on the spicules, which are relatively so constant in 
form and arrangement as to be of the first importance in the 
determination of genera and species. There are only 3 different 
forms of spicules in calcareous sponges — (1) simple needles, (2) 
3-rayed needles, (3) 4-rayed needles, each of which builds up the 
skeleton alone or in combination. The 2-rayed needles, which he 
formerly thought to form another group, are only a subordinate 
condition of the first. Only 7 forms of skeleton are therefore 
possible, all of which exist in nature ; and Hackel consequently 
divides the calcareous sponges into 21 genera, to which he 
applies wholly new names, because his genera do not correspond 
to those of his predecessors [a most reprehensible proceeding, 
in the face of the confusion which exists already in all branches 
of natural history, in consequence of the unconscious or wilful 
disregard of the law of priority by various authors], and adds 
the following table : — 
Skeleton-structure. 
Spicula all simple 
Spicula 3-rayed 
Spicula 4-rayed 
Spicula simple and 3-rayed .... 
Spicula simple and 4-rayed .... 
Spicula 3- and 4-rayed 
Spicula simple, 3- and 4-rayed . . 
Ascones. 
Leucones. 
Ascyssa. 
Ijcucyssa. 
Ascetta. 
Leucetta. 
Ascilla. 
Loucilla. 
Ascortis. 
Leucortis. 
Asculmis. 
Leuculmis. 
Ascaltis. 
Leucaltis. 
Ascandra. 
Leucandra. 
Sycones. 
Sycyssa. 
Sycetta. 
Sy cilia. 
Sycortis. 
Syculmis. 
Sycaltis. 
Sycandra. 
K. JAnos notices llackel’s views respecting the affinities of the Sponges 
with the Ccelenterata, Term. Kozl. 1871, p. 147. 
E. Eulers (Z. wiss. Zool. xxi. pp. 540-567) proposes to call 
the sponges without pores Spongias holosarcin(Bf and the others 
Spongim cailosarcAn<je. The chief points of importance in the 
classification of the sponges are the arrangement and extent of 
their porous system, and the differences in the sponge-body 
itself. The lowest form of the Ccelosarcincs is Cellulophana pi- 
leata, Schmidt ; and the next Veluspa polymorplia, Mikl.-Macl. 
The large cavity arising from a development of a section of the 
ccelenteric spaces may be called a megacodon, and its opening a 
megastoma] but the cavity arising by regular division of the 
whole sponge-body he calls a codoma, and its opening a codo- 
stoma. There is but little affinity between the Sponges and 
Codenterata, although the coenostoma and coeloma of a sponge 
appear to be homologous to the mouth and body-cavity of the 
Codenterata, and the pores of the epidermis of the latter to the 
