and Specien of Nudibranchiate MoUusca. W'.\ 



twenty-five laniiiut' ; tliev are retractile within cavities, the 

 margin.s of whiciiare produced iiitoshortslicatii.'^. Tiie Itranchia} 

 arc small, slender, bushy, dividing dichotoniou.sly, and arising 

 from six roots, three being at each side of the anus ; there is 

 a considerable interval between the anterior roots ; and the 

 posterior ones bear numerous and .smaller plumes. The anus, 

 situated almost between the last, is wide and tubular, and has 

 the posterior wall more produced than the anterior. The 

 common cavity, into which the branchiai and anus are re- 

 tractile, has the margin raised. The mouth is subtenninal, 

 opening rather downwards ; on each side is a conspicuous pit, 

 into wliich it is possible that a small tentacle may be retractile 

 by invagination. The foot is linear, with a wavy edge, ante- 

 riorly lobulatcd inwards. The colour of the spirit specimens 

 is a brownish cream or pale fawn, sparingly marked with 

 whitish, tubercular, or slightly raised, unequal, rounded, ocel- 

 lated spots, which are rather more numerous on the sides ; a 

 row of five or six of these spots extends along the medio- 

 dorsal line from in front of and between the dorsal tentacles ; 

 the margins of the branchial and tentacular cavities are sur- 

 rounded by a row of such spots. 



Dimensions (in spirit) : length 48 millims., breadth 15, 

 height 18, length of tail 9. 



Hab. Australia. 



C. brevi'caudatitm presents many points of resemblance to 

 the following species (C. oblongum). 



Ceratosoma oblongum, sp. nov. PI. VII. figs. 7,7 a, 7 b. 

 C. elongato-oblongum, prismaticum, laeve, fuscum, nigrescentibus 

 maculis rotundatis sparse oruatum; dorso oblongo, non lobato et 

 non levato; tumore postbranchiali parvo, rotundato, uodulari ; 

 Cauda brcvi ; tentaculis dorsalibus parvis, conicis, acutis, arrectis, 

 lateraliter comprcssi.s, in cavitates retractilibus ; branchiis 18 + , 

 ramosis, ex sex radicibus orientibus, ante anuni circulariter positis, 

 in foramen coramuno retractilibus ; pedc lineari. 



The body is oblong, smooth, prismatic, not raised in the 

 branchial region ; the dorsal surface is rather curved, and 

 shows but little trace of constriction or lateral lobation. The 

 postbranchial protuberance is small, rounded, and nodular; 

 and between it and the origin of the short subconical tail 

 there is but a verj- small interval. The dorsal tentacles are 

 conical and pointed, laterally flattened, diagonally laminated, 

 directed rather forwards and outwards, and retractile within 

 cavities. The branchiai are about eighteen in number, slender, 

 and placed in a semicircle in front of the anus ; those at the 

 sides are rather longer. The four anterior, with an interval 

 between the two foremost, arise separately ; the others, six on 



