SPONGOZOA. 
4 Spong. 
Under the name of Physemaria, Hackel (5) proposes a distinct class, 
intermediate between Hydrozoa and Sponges, or rather a sub-class of 
Sponges, distinguished from the true “ poriferous ” Sponges by the 
absence of pores, and from the Hydrozoa by the want of nematocysts. 
They are sessile animalcules of a most simple organization, consisting only 
of a membranous sac-shaped body, provided with a terminal mouth and a 
short stem, through the dilated base of which they are fixed, sponge- 
fashion, to foreign bodies on the sea bottom. The body-membrane 
consists only of two layers : an endoderm of flagellate cells, and an ecto- 
dermal syncytium, in which are immersed grains of sand, sponge-spicules, 
shells of Foraminifers and Radiolarians, Coccoliths, &c., selected and 
arranged in a manner peculiar to each species. A more or less developed 
spiral line of larger flagellate endodermal cells governs the afferent and 
efferent water-currents. The ova are metamorphosed endodermal cells, 
in some species confined to the basal portion of the body-cavity, the 
superior portion whereof may be furnished with glandular cells, which 
are differentiated epithelial cells. The evolution and segmentation of the 
egg and formation of the gastrula-stage by invagination were observed 
in Gastvophysema. From Hackel’s hypothetical (extinct ?)“ GastrceadceP 
they only differ in their fixed (not free swimming) condition in the adult 
state. Two genera are known : Haliphysema primordiale, sp. n., Hackel 
(Z. c. p. 180, pi. ix.), Mediterranean ; H. echinoides, sp. n., id. 1. c. p. 186, 
pi. X., Norway, probably = Wyvillethomsonia wallichi, Wr.) ; II. glohi- 
gerina, sp. n., id. 1. c. p. 189, pi. xi.. North Sea, deep water; H. tumano- 
wiczii. Bow., and H. ramulosum, Bk. [compound !]. Gastvophysema, g. n., 
Hackel ; body cavity divided in a series (two to five) of chambers ; G. 
dithalamium, sp. n., Hackel (p. 196, pis. xii.-xiv.), Mediterranean; also G. 
scopula (Cart.), wrongly referred to Squamulina, according to Hackel. 
Gicnera and Species. 
Carter (4) describes and figures the following : — 
Grantia ciliata, FI., var. spinispiculum, p. 468, pi. xii. figs. 6 -8 (Shet- 
land, 64-75 fathoms). 
Halisarca cruenta, sp. n., p. 228 (North of Cape St. Yincent, 374 
fathoms, on Corallistes and other sponges). 
Corticium parasiticum, sp. n., p. 229, pi. xvi. fig. 25 (English Channel, 
862 fathoms). 
Aplysina ncevus, sp. n., pi. xii. figs. 2 & 1 C (N. of Scotland and Shetland, 
170-345 fathoms). 
Spongia officinalis, p. 231, pi. xii. fig. 1 a (with the preceding). 
Spong elia pallescens, Sdt., p. 232 (155 fathoms'!. 
Dictyocylindrus abyssorum, sp. n., ibid. pis. xii. fig. 3, xv. figs. 25, a, b, 
and simplex, sp. n., p. 234 (N. of Scotland, 345-440 fathoms) ; virgultosus, 
Bk., id. 1. c. pi. xii. fig. 5, pi. xv. fig. 27 (Shetland, 64-75 fathoms). 
Plumohalichondria microcionides, sp. n., p. 236, pi. xii. fig. 11, pi. xv. 
fig. 30 a, b (N. of Scotland, 440 fathoms). 
Microciona jejusculum, Bk., p. 237 (Hebrides, off Capo St. Vin- 
cent, 374 fathoms, Ftero, 114 -fathoms) ; longispiculum, sp. n., pi. xii. 
