REPORT ON THE CRUSTACEA MACRURA. 349 



furnished with a short, obtusely pointed stylocerite (the rest of the appendage is 

 destroyed). 



Second pair of antenna? carries a large scaphocerite but no ancecerite (the flagellum 

 is lost). 



The epistorna is thin, membranous and lunate. 



The cheiloglossa is large, curved and wide. 



The mandibles are deeply placed within the oral aperture, and have the psalistoma 

 smooth and continuous with the molar process, at the base of which a long, two-jointed 

 synaphipod exists. 



The first pair of siagnopoda is three-branched, the second four-branched, and carries 

 a mastigobranchial plate, the third is three-branched, the inner branch being broad, 

 foliaceous and Particulate, and fringed with hairs upon the inner side, the second or 

 middle branch long, slender and triarticulate, and the third or outer long, slender, 

 tapering, and free from hairs. 



All the other appendages except the pleopoda are too much broken to allow their 

 form to be determined. 



The telson, which is perfect, is long, slender and tapering, but not so long as the 

 lateral plates of the rhipidura, which are broken off in all our specimens. 



Geographical Distribution. — Only one species of this genus is known, and that was 

 taken in two localities, one near Marion Island and the other south of Australia. 



The great distinction between this genus and Sergestes exists in the form, character, 

 and arrangement of the branchial plumes, which consist of a series of plates and 

 cylindrical filaments situated side by side in a series of rows at right angles to the stalk. 

 There is but one plume to each of the five anterior somites of the pereion, the posterior 

 two somites having none ; between some of the somites is a large foliaceous plate. The 

 arrangement may be tabulated thus : — 



Pleurobranebia?, . . f f f 



Artbrobrancbis, . . . r 1 1 1 1 



Podobrancbiae, . . . 1 



Mastigobrancbiae, . . . 1 



b i k 1 in n o 



Petalidium foliaceum, Spence Bate (PI. LX.). 



Petalidium foliaceam, Sp. B., loc. cit., p. 194. 



Anterior margin dorsally elevated to a small, laterally compressed crest, produced 

 in front to a very small point ; body generally smooth. Ophthalmopod subcylindrical, 

 long ; ophthalmitis not broader than the diameter of the stalk, furnished on the inner 

 side with a small tubercle, close to the dark pigment. Dark brown hairs on the oral 



