34 CHELIDONURA. 
in the outer lip which is acute, very thin, arcuate and in the middle 
subimpressed ; posteriorly it is produced in a rounded lobe, separ- 
ated from the body of the shell by a profound sinus. 
Alt. 2, diam. 2% mill. 
Drobak, 70-80 fms.; Vallé 200-250 fms. 
Colobocephalus costellatus M. Sars, /. ¢., pl. 11, f. 7-14. 
Fig. 6, animal from above, magnified 10 diameters, showing head- 
processes, anterior lobes of foot (pleuropodia), and truncate tail. 
Fig. 7, animal from below. Fig. 8, lateral view. Figs. 9-11, the 
shell. Pl. 9, fig. 8, half row of radula denticles. 
Genus CHELIDONURA A. Adams, 1850. 
Chelidonura Av., Thes. Conch., ii, pp. 561, 601.—Chelinodura 
FiscHeR, Manual de Conchyl., p. 564.— Hirundella Gray, Figures 
of Molluscous Anim. iv, p. 95, type “ H. hirundinaria” (1850); 
Guide Syst. Dist. Moll. B. M., p. 193. 
Shell concealed in the mantle, small, ear-shaped, thin and fragile, 
subspiral, composed of one whorl; aperture very large, rounded be- 
low, the outer lip produced far above the vertex in a long, acute, 
curved process. 
Animal elongated, the front margin of the head-disk armed with 
bristle-like sense-organs, its posterior lying over the back in a long 
tongue-like lobe. Mantle produced behind in two tail-like pro- 
cesses; foot truncate and subauriculate in front, rounded behind, 
the mantle-appendages projecting behind it ; parapodial lobes long, 
curving over the head-shield and back. Dentition unknown. Type 
C. hirundinina Q. & G. 
This genus differs from Philine in the more reduced shell, the 
peculiar sense-organs of the head, the long posterior mantle-processes 
and brilliant coloration of the animal. The species are from Mau- 
ritius and east Australia. 
C. HIRUNDININA Quoy & Gaimard. Frontispiece, figs. 15, 10; 
Pl. 2, figs. 25, 26, 31-35. 
Shell small, fragile, entirely open; white; right margin flat, 
winged, acute posteriorly. 
This singular Bulla is an inch long. The head presents three 
little bunches of short bristles in front. The posterior append- 
age, bifurcate in the other species, has no lobes, but ends in a 
simple lanceolate tongue, extending over the back. A transverse 
