and Species of Nudibranchiate Molliisca. 141 



In the diagnosis of the genus given by Adams and Reeve* 

 the dorsal tentacles are said to be non-retractile — a statement 

 repeated in Bronn's ' Thierreich 'f, although corrected in Alder 

 and Hancock's ' Synopsis ' |. They are certainly retractile in 

 the four species represented in the British-Museum collection. 



The following species of Ceratosoma have been hitherto 

 figured: — C. corm(/erum, Ad. & E,eeve§ {=Doris trifida, 

 Gray), G. trilobatum, Gray, a,nd. C. graciUimum, Semper ||. 

 The first alone has been described. 



Ceratosoma teaue, sp. nov. PL VII. figs. 5, 5 a, h. 



C. triangulare, prismaticum, lateraliter compressum, molle ; dorso 

 piano, leviter trilobato ; tumore postbranchiaH complanato ligu- 

 lato ; colore fiilvescenti-lacteo, punctulis pallidioribus maculato, 

 et lineis reticulatis remisse notato ; tentaculis dorsalibns brevibus 

 clavatis, ad apices rotimdatis, minute laminatis, in foramina an- 

 gusta profundaqne retractilibus ; branchiis magnis gracilibus ante 

 tubulatum anum, e tribus radicibus orientibus, in foramen retracti- 

 libus; ore utriusque parva depressione praedito, pede lineali usque 

 Unem longae caudae extenso, margine antice lobulato et inflecto. 



The body is prismatic, and is triangular in lateral outline, 

 raised in the central branchial region, smooth and soft. The 

 mantle is obsolete. The dorsal surface is flat or gently curved, 

 and a little constricted behind the dorsal tentacles ; it gradually 

 rises from above the mouth, and culminates behind the branchise 

 in a flattened, ligulate, roundedly pointed fleshy appendage. 

 Beneath the latter the body falls abruptly, and then curves off 

 into the laterally compressed, elongated tapering tail, which 

 occupies about four tenths of the total length of the animal. The 

 thickened and slightly overhanging border of the supracapital 

 surface is marked by a rather thick semitransparent line lying 

 between two opaque irregular ones. Two pairs of short, 

 curved, similarly bordered lines are found upon the sides of the 

 dorsal surface, and a somewhat similar marking margins the 

 postbranchial protuberance. The dorsal tentacles are short, 

 clavate, rounded at the apex, and minutely and diagonally 

 laminated ; they are retractile within deep narrow cavities, 

 which have the border slightly protuberant. The branchiee, 

 about twenty-one in number, are long and slender, and arise 



* ' Zoology of the Voyage of II.M.S. Samarang,' Mollusca, pp. 67 & 

 68, pi. xix. f. 5. 



t ' Thierreich,' Band iii. p. 798. 



+ * Monograph of the British Nudibranchiate Mollusca,' Appendix, 

 p. xix. 



§ Loc. fit. 



\\ ' Reisen im Archipel der Philippinen,' Theil 2, Baud ii. Heft o, t, 2.5. 

 f. 8. 



