NEW GENERA AND SPECIES, ANATOMY, &C. Spong, 11 
Bpiculation and structure they respectively resemble Leuconia johnstonia 
and Grantia compressa. 
Wagnerella. Mereschkowsky (13), p. 76, p- 15 of the St. Petersburg 
Memoir. An Asconidean Calcisponge, consisting of peduncle containing 
short acerates, and of head echinated by fine acerates asTeell. W. hwealis, 
Mereschkowsky (13), p. 76, pi. vi. ; p. 22, pi. ii. figs. 1-5 of the St. Peters- 
burg Memoir, in White Sea. No oscula or pores discovered, the basal 
cone (similar exteriorly to that of Haliphysema) is probably the oldest 
part, the head is formed by the swelling of the peduncle. 
Anatomy and Physiology. 
“ Individual ” in Sponges is limited, (14)"p. 37, to a single gastral cavity 
with a bipolar axis. Thus the Sycones are entirely colonial forms, and so 
is Halisarcd. 
Three tissue-layers distinguished in Sponges (18), viz., (i.) outer cell 
layer, (ii.) connective tissue, (iii.) collar-cell layer; not to be ranked 
with certainty as separate embryonic layers. Outer layer consists of flat 
polygonal cells in Spongelia avara. 
Hinder pole of embryo ciliated in Spongelia pallescens and Euspongia 
(18). 
Halisarcce seen to have three body-layers and cellular dermal epithe- 
lium (9). 
Epidermis of a Halisarca (14), p. 33, formed of flask-shaped glandular 
cells. 
Long spindle-shaped cells surround the excretory passages of Aply- 
sina aerophoba (15), and are perhaps muscular in function. 
Amoeboid wandering-cells apparently found in mesoderm of Aplysina 
(15), certainly in Aplysilla. 
Pigment cells of Aplysina (15) considered as reserves of nutritious 
matter. 
Spindle-shaped cells of Reniera semitubulosa^ &c., probably not mus- 
cular ; the same sponge possesses nutritive wandering cells (9). 
A muscular sphincter described, (14) p. 31, in a Halisarca. Cf. (10) 
figs. 35 & 37, for sponge-cells and spores. Acinetoid stage of sponge-cell 
(10) in Grantia compressa. In support of the Protozoan theory of the 
origin of Sponges (10), the transparent subdermal intercellular substance 
is supposed to be mere exudation from the collar cells, and the cells 
contained in it to be their transitional stages ; a further intermediate 
stage being a simple flagellate form as shown in Halichondria panicea^ 
pi. iii. fig. 32. 
Pointed spicules may have the non-pointed end projecting from the 
surface of the sponge {e.g.y many anchoring spicules) (1). 
Sudden narrowing of pointed end of some spinulate spicules mRinalda 
arctica^ sp. n., among other variations (14). 
Diaphragms of spinular spicules with heads outwards occur in burrows 
of Cliona, 2 spp. nn. (19) ; and a mucronately pointed spinular spicule, a 
new form, in Cliona mucronata (19). 
Size, as a fundamental point in spicules, not considered binding as a 
