36 
shaped, arising from the angles of the head, grooved laterally and 
diverging anteriorly, Foot narrow. No distinct respiratory organs. 
49. PrEROGASTERON ORNATUM. 
Body smooth, and when expanded of an orbicular form; when 
erect, in their natural state, very high and much undulated. Ten-- 
tacles grooved their whole length and slightly truncated. Colour 
olive-green, paler along the foot, spotted with faded yellow, and 
dotted with black. Body margined with bright orange-red and 
edged with black, in which are a few white dots. Upper surface of 
the body paler than below, punctured with black and light red, and 
margined the same as beneath. 
Hab, On the rocky coast, among sea-weed. 
50. PrEROGASTERON BELLUM. 
Body smooth, when expanded of an oblong-ovate form, and when 
in their natural position are quite low when compared with prece- 
ding species. The posterior portion is acutely rounded. Tentacles 
stout and truncated. Colour brownish-red, and closely spotted with 
small, irregular, greyish-white spots. Eyes with white areolee. 
Length 1 inch. 
Genus HistiorHorvws. 
Animal.—Oblong, no distinct mantle. Body rounded ; posterior 
portion prolonged into a vertically compressed tail, furnished above 
with a membranaceous crest. Branchiz three, inserted at the middle 
portion of the dorsal region. Dorsal tentacles, no labial appendages. 
Head furnished with a veil. Foot linear. 
51. HistriopHORUS MACULATUS. 
Form oblongo-ovate, smooth, subpellucid. Three tufts of filaments 
on each side, disposed longitudinally, and also two on dorsal region ; 
to each of the hinder tufts is attached an oval glandular body. 
Branchiz rather large, procumbent, retractile (?), fimbriated, one di- 
rected anterior, which is simple, the remaining two lateral and bifur- 
cated. Anal tube prominent. Dorsal tentacles oblongo-ovate, mu- 
cronate, slightly compressed, retractile? and finely lamellated trans- 
versely. Head furnished with a transversely oval veil, which is 
broader than the body, and fimbriated around the margins with 
small tufts of filaments. Foot linear, extending the whole length of 
the body. Mouth simple. Colour pale whitish-ash, irregularly 
dotted with orange above, and four small crimson dots near base_of 
branchial plumes. Branchiz pale and freckled with brown. Dorsal 
tentacles green-olive, tips pale. Veil yellow. 
Length 14 inch. 
An active animal, using its compressed tail for swimming. 
