JOURNAL OF MICROSCOPICAL SCIENCE. 
EXPLANATION OF PLATES XXX AND XXXI, 
Illustrating Professor Ray Lankester^s Memoir on “ Lirnno- 
codium (Craspedacustes) Sowerbii, a new Trachomedusa 
inhabiting fresh water.^^ 
Fig. 1. — Enlarged sketch of a quadrant of the disc of an immature 
specimen of an inch in diameter) seen from the subumbral surface. 
Per T. two of the perradial tentacles ; Ax. endodermal axis of same ; MR. 
marginal ring (nettle-ring, peronia, and endodermal ring tissue) ; MC. 
marginal canal ; RC. radial canals ; VMC. velo -marginal cells ; Ve. velum 
in winch are seen the ‘‘ velar centrifugal canals ” or tubular capsules of the 
marginal bodies. Just above Ve. two neighbouring capsules are seen to have 
coalesced ; Go. the immature outgrowths of the radial canals, in the ecto- 
derm of which the generative products are formed ; St. stomach. 
Fig. 2. — Edge of the velum as seen when reflected, showing the position 
of a tubular “otocjstic” capsule between the two layers of the velum; ot. 
tubular capsule; Sup. abumbral ectoderm-layer of the velum; Inf. the 
adumbral musculo-epithelial ectoderm of the velum ; Vac. vacuolated cells 
of the abumbral ectoderm, which by fusion cause the increase of the 
tubular capsule ; muse, circular muscle-fibres of the adumbral ectoderm (not 
shown in the lithograph). 
Fig. 3. — Diagram of a section through the edge of the disc to show the 
relation of the tentacle-root to the endoderm of the marginal canal ; Ec T. 
ectoderm of the tentacle; EnT. endoderm of the tentacle; EcD. supra- 
umbral ectoderm of the disc; EcD'. subumbral ectoderm of the disc; 
Ee V. abumbral ectoderm of the velum ; Ec V. adumbral ectoderm of the 
velum ; NR. nettle-ring, viz. ectoderm of the marginal ring charged witli 
thread-cells ; En R, endoderm of the abumbral wall of the marginal canal, 
having a cartilaginoid character and greenish-yellow colour ; VMC. one of 
the strongly marked row or ridge of endodermal cells termed “ velo-marginal 
cells En L. position of the endoderm-lamella of the disc ; x. ring of 
colourless ectodermal cells, being the abumbral portion of the nerve-ring ; 
Li. marginal body ; Cap. tubular capsule of the marginal body ; ot. cavity 
of the tubular capsule ; MC. marginal canal. 
Fig. 4. — View from tlie supra-umbral surface of a portion of the 
marginal ring; the ectodermal cells only arc drawn. T. tentacle ; 2'R. ten- 
tacle-root ; Ec D. ectoderm of the supra-umbral surface of tlie disc ; Pe. 
peronium ; NR. nettle-ring ; Ec V. ectoderm of the abumbral surface of 
the velum ; VMC. row of vclo-marginal cells (endodermal) showing through 
the ectodermal cells of the nettle-ring. 
Fig. 5. — The same preparation more deeply focussed. 2' R. tentacle- 
roots formed by notochordal tissue; R End. cartilaginoid endoderm of the 
marginal canal (representing the “ ring-cartilage”) ; MCa. adumbral wall of 
the marginal canal in section, showing soft ciliated cells with contained 
granules (enlarged in fig. 7) ; Mcp. the inferior border of tlie marginal 
canal formed by the velo-marginal cells, marked VMC in other figures ; A', 
nerve-ring; EcV. adumbral ectoderm of velum; MB. marginal body; 
CC. tubular capsule of the same. 
Fig. 6. — Transition of the pale notochordal tissue of a tentaclc-root into 
