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THE VOYAGE OE H.M.S. CHALLENGER. 
side of the mucous gland, its colour is brownish-yellowish ; the cavity was empty. On 
the upper side of its duct is the strong crescent-shaped white vestibulo-vaginal gland, 
2‘5 mm. in length and 1 ‘3 mm. in height. 
Whether this species is identical with Doriopsis nebulosa, previously described by me, 
or not, must be for the present left undecided ; in external appearance at any rate it is 
very like Doriopsis nebulosa. 
APPENDIX. 
Family Orchidia da:. 
Pulmonata (non testacea) doridiformia; limbo palliali plus minusve prominenti, recto 
vel undulato. Dorsum papillis vel tuberculis simplicibus vel compositis, interdum 
frutescentibus, ut plurimum pro parte ocelligeris obtectum; clypeus frontalis (subpallialis) 
fortis angulis tentaculiformibus, et postice rhinophoriis (ophthalmophoriis) exsertilibus 
cylindricis, juxta apicem ocelligeris. Pneumostoma posticum medianum vel submedianum 
infrapalliale ; infra pneumostoma anus. Secundum totam longitudinem lateris (humilis) 
dextri corporis sulcus genitalis (fcemininus), juxta porum glandulae pcdiaese medianum, 
supra podarium antice situm, desinens ; in parte postrema sulci vulva. Apertura genitalis 
masc.n l in a in facie superiore clypei frontalis submecliana vel fere infra rhinophorium 
dextrum sita. Podarium latum. 
Bulbus pharyngeus fere semper sine mandibula. Ventriculus compositus. 
Yas deferens pro parte latere corporis inclusum, sulco genitali contiguum, deinde 
liberum, longissimum, ut plurimum ultima parte seriebus uncinorum armatum. Glandula 
cum ampulla et hasta amatoria ut plurimum non desunt. 
The Onchidiadae are specially modified shell-less Pulmonates, and resemble somewhat 
the Dorididae in outward form, and therefore were included in the Nudibranchiata by cle 
Blainville. They resemble also the typical Doris in having a thick straight or sinuate 
mantle-brim. The dorsal surface is uneven, more or less densely covered with papillae 
and tubercles, which are simple or compound ; sometimes, especially in the hinder part 
of the body, they are frutescent ( Peronia ) ; these papillae very usually bear groups of 
eyes, which have the structure of vertebrate eyes. 1 In front, below the mantle edge 
and above the mouth, is a strong, roof-like frontal shield ; at the base of this and above 
1 Semper, Reisen im Arehip. <1. Philipp., Th. IT. Ed. iii., Landmollusken, Erganzungsheft, Ueber Sehorgane vom 
Typus der Wirbelthieraugen. m. 5 Taf., 1877. 
