and Species of Nudihranchiate Mollusca. 137 



somewhat subprismatic, and in having the mantle more or 

 less pustulose, with its fore lateral and posterior border rather 

 thick and comparatively but little expanded. //. lacera differs 

 from H. pellucidula in bearing distinct, large, soft, rugose 

 pustules upon the back, and in having the mantle-border 

 deeply dissected and crenate. 



Hexahranchus suezensis, sp. nov. PL VI. figs. 3, 3 a. 



H. ellipticus, crassus, ad dorsum et subtus ad latera subpellucidu- 

 lus ; pallio lato, piano, margine tenui integro sed raulto plicato ; 

 tentaculis dorsalibus parte supcriore conica laminata, reflexa, 

 prorsum confevtisque positis et in vaginas breves retractilibus ; 

 branchiis numerosis, parvis, museosis, non-retractilibus, in sex 

 cristis anum hand propiuque circumdatis ; tentaculis labiali- 

 bus magnis, crassis, ovatis, margine multilobulato ; pede angusto, 

 antice et postice rotundato, antrorsum cum transversa fossa brevi. 



The general form is elliptic ; the body is rather fleshy and 

 somewhat semitransparent on the back and, underneath, on 

 the sides. The mantle is smooth, with the expansion wide, 

 especially posteriorly, and rather leathery in large specimens ; 

 its edge is thin and nearly smooth, and greatly folded or fim- 

 briated ; the origin of the lateral expansion is high in the 

 middle region, but lower towards -the head and near the bran- 

 chife ; in front the expansion is small, with the border thicker 

 and more or less recurved. The dorsal tentacles are rather 

 slender, with the upper half conical, sharply bent back (the 

 angle being forwards and outwards) , and having about seventy 

 diagonal and wavy laminaj proceeding from a slight, superior, 

 longitudinal depression. The lower laminae do not extend 

 round the tentacle. The cavities into which the tentacles are 

 retractile are set far forwards and close together, and have 

 the margins produced into short smooth sheaths. The bran- 

 chiae are small, complex, and dendritic in appearance ; they 

 are placed in six non-retractile tufts at some distance around 

 the subcenti-al anal opening. The oral tentacles are large, 

 fleshy, ovoid or leaflike, with a multilobulate border. The foot 

 is narrow, rounded, and transversely grooved in front, rather 

 acuminated, rounded, and with a small portion free behind. 

 The mouth, large and exsertible, leads into a cavity, the lateral 

 walls of which bear short, longitudinally striated, subcorneous 

 jaws : the broad, heart-shaped odontophore is divided by a 

 median longitudinal depression, above which the lobes are 

 applied together and bear about twenty-two transverse rows 

 of numerous, elongated, simple, recurved, pointed spines, nono 

 of which are central in position. The general colour, in the 



