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. 2f mill. 



Drobak, 70-80 fms. ; Valid 200-230 fms. 



Colobocephalus costellatus M. SARS, /. c., pi. 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. PI. 9, fig. 8, half row of radula denticles. 



Genus CHELIDONURA A. Adams, 1850. 



Chelidonura AD., 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; 

 PI. 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 



