2 
Kinetocodium danæ n. g., n. sp. 1 ) 
Description: The colony grows on the shell of Hyalæa 
( Diacria) trispinosu Lesueur; it consists of creeping stolons, nutri- 
tive polyps, and medusoid gonophores. 
The nutritive polyps are placed on the foremost part of the 
pteropod shell (Plate I, fig. 1), mainly on the dorsal side close to 
the frontal margin and, ventrally, just behind the mouth of the 
shell; no polyps are found behind the lateral spines. The gono¬ 
phores, on the other hånd, are mainly found on the hind part of 
the shell, particularly along the lateral margins, though a good 
number are scattered over the ventral surface behind the mouth; 
only a few gonophores are placed on the dorsal side of the shell, 
and then only on the narrow part, the back spine. 
The stolons form a meshwork of anastomosing threads run- 
ning over the surface of the pteropod shell. The coenosarc is a 
narrow cylindrical or somewhat flattened tube not exceeding O.04 
mm in breadth; the cell layers are thin, particularly the ectoderm 
which consists of very large, flattened, polygonal cells (PI. I, fig. 6). 
The coenosarc is surrounded by a very thin perisarc forming a del- 
icate tube, very much flattened and several times broader than 
the coenosarc tube. Below each nutritive polyp the stolons are 
somewhat thickened, forming a kind of foot to the polyp (PI I 
fig- 2). 
The nutritive polyps (PI. I, fig. 2) are naked ; the delicate 
perisarc of the stolon stops somewhere at the foot of the polyp, 
but lts limit cannot be distinguished. Each hydranth is borne by 
a long, siender, cylindrical pedicel, about IV 2 —3 mm in length 
and 0.2 mm wide. Near the base the pedicel is abruptly bent at 
a right angle; this is not a casualty due to preservation, but a 
constant feature, causing the polyp, in its normal position, to be 
stretched horizontally over the support. 
The histological structure of the pedicel shows some interesting 
peculiarities. Between the ectodermal epithelium and the complexly 
folded endoderm is the mesosarc, which is considerably thicker than 
is usually the case in hydroid polyps. This thickening of the meso- 
) From. xivijTog, movable and xujåiov, diminutive of y.coac, fur. 
