Fam. 3 , Plate 17.
%■ IEOLIS
SMARAGDINA, Alder and H ancock.
,R. gracilis, dba, pellucida; capite onto; bramchiis effiptico-oblongis viridibus, apicibus albis,
faseiculis 5 digestis; tentaculis dorsalibus et labialibus longiusculis, aaqualibus; angulis anterionbus
pedis productis.
Hab. Among sea-weeds between tide-marks, very rare. Whitley, Northumberland, A. H.
Body about half an inch long, slender, pellucid, white, with most of the small branches
of the gastric system appearing through the skin of a pale green colour. Dorsal tentacles
rather long, slender, smooth, and tapering, transparent white, or nearly colourless. Oral
tentacles of the same length as the.dorsal pair, and equally destitute of cblour or markings;
their external bases form the sides of the head, which is very short. Branehia rather large,
elliptical, or nearly linear; the central vesselof an emerald green colour; the tips pellucid,
with a slender rin'g of opaque white. They are arranged down the back in five well-defined
clusters. Foot slender, pellucid, produced at the angles into moderately long processes.
We have taken only one individual of this Eolis. It occurred at Whitley, in June, 1843,
crawling upon the common Fuats vesicidosus. This position was most likely accidental; at
least it must not be taken as a proof that the speciesris less carnivorous than its congeners,
for we saw it, during its captivity, seize and actually devour a portion of a living F. gracilis
that was in the same glass with it.
The nearest allies of E. smaragdina must be looked for among the Eolides with red
branchiae, as no other green species that we are acquainted with belongs to the same section of
the genus. It approaches very near to E. gracilis, from which it differs chiefly in the colour
of the branchiae and the shortness of the head.