REPORT 0!ST THE NUDIBRANCHIATA. 
79 
Ceratosoma, Adams and Reeve. 
Ceratosoma, A. Adams, Voyage of the “ Samarang,” Mollusca, 1848, p. G7. 
,, Bergh, Malacolog. IJntersuch. (in Semper, Reisen im Archip. d. Philipp. Th. II. 
Bd. ii.), Heft s., 1876, pp. 391-410; Supplementheft i., 1880, pp. 28-31. 
Corpus subcompressum, postice gradatim altius ; nothaeum postice trilobatum, lobi 
laterales breviores et rotundati, posterior linguiformis ; rhinoplioria retractilia, clavo 
perfoliato ; tentacula brevia ; podarium sat angustum, cauda elongata. 
Armatura labialis fortior, e hamulis minutissimis formata. Radula rbachide nuda, 
pleuris multidentatis ; dentes hamati. — Penis inermis. 
This genus was established by (Gray 1 ) Adams and Reeve, in 1848 ; the definition given, 
however, was only superficial and entirely useless. 2 Alder and Hancock 3 corrected several 
of the mistakes made by these last-mentioned authors. The next contribution to the 
literature of the genus was a small memoir published by myself in 1876. 
Ceratosoma is at once distinguishable by its peculiar form. The head is rather flat, 
with a short frontal margin prominent at the edges ; the club of the retractile rhino- 
phoria is provided with the usual leaves. The tentacles, as those of Chromodoris, can be 
quasi-invaginated. The body is higher behind than in front ; on either side of the hinder- 
most portion of the flattened dorsal surface is a rounded lobe, behind the back ends in a 
tongue-shaped process ; in front of this is the circular opening for the retractile branchia. 
The foot is narrow and small, but the tail strong and long. The armature of the labial 
disk rather strong and composed of a number of closely-set minute hooks. The radula 
has a bare rhachis, numerous hook-shaped lateral teeth on either side. The penis is 
unarmed. 
The genus is apparently confined to the tropics, and lives, according to Adams, 
crawling upon the surface of Madrepores. 
Only a few species are properly known, but a number of new forms have been 
published by Fischer and by Abraham. 4 
1 Alder and Hancock, Woodward, and other authors regard Gray as having the priority. The name Ceratosoma is 
to be found in vol. iv. of his Figures of Molluscous Animals (pp. 13, 42, 105 : “back produced behind”), which appeared 
in 1850. The Malacological part of the Voyage of the “Samarang” bears on its title page the date 1848, and in this 
volume the genus Ceratosoma is described and marked “ nov. gen.” ; according to the chief title, the V oyage of the “Sama- 
rang” did not appear until 1850. The question of priority, therefore, is difficult to settle. Perhaps Adams’s drawing 
actually passed through the hands of Gray (e/. Journ. des Museum Godeffroy, Heft vi., 1874, p. 95, Bornella), or possibly 
the latter formed the genus on the species Boris trilolata, figured by him in 1842. 
2 The English authors mention the rhinoplioria as not being retractile, and their description of dorsal processes is 
rather confused, cf. Woodward, Manual of the Mollusca, vol. ii., 1854, p. 192. 
3 Alder and Hancock, Monogr. Brit. Nudibr. Moll., pt. viL, 1855, App. xix. 
4 MM. Crosse and Fischer, like Mr. Abraham, have been recently studying the Nudibranchiata. The former authors 
have increased the genus by one new species, but they regard Ceratosoma as closely allied (“ trks voisin ”) to Thecacera, 
Polycera. Aegirus, &c. ( !), and are unable to distinguish Goniodoris from Chromodoris , and Doriopsis from Doris. 
