Limacina.] PTEROPODA. 57 



Fam. LIMACINID^E, Gray. 

 Spirialidae, Chenu. 



Animal with, a dorsal pallial cavity, and a ventral columellar muscle ; 

 anus situated on the right side. The animal is twisted like the shell, 

 which it completely fills, and into which it may be completely retracted. 

 The margin of the mantle bears, on the right-hand side, and some- 

 what ventrally, a long extensile appendage. The posterior lobe of 

 the foot, which bears the operculum, and is topographically ventral, 

 is hollowed out on the middle of its free margin. The fins do not 

 exhibit towards their distal extremity an area without muscular fibres. 



Shell very delicate, external, twisted into a left-handed spiral, small, 

 translucent, with slight colouring. Operculum spiral, very delicate, 

 glassy, and transparent. It is fixed by a portion of its surface to the 

 posterior face of the ventral lobe of the foot. 



Genus 1. LIMACINA, Cuvier, 1817. 



Limacina, Cuvier, " Regne animal," ii, 1817, 380. Type : Clio helicina, 

 Phipps. Heterofusus, Fleming, 1823. Spiratella, de Blainville, 1824. 

 Heliconoides, d'Orbigny, 1836 (in part). Spirialis, Eydoux and Souleyet, 

 1840 (in part). Helicophora, Gray, 1842. Scce-t, Philippi, 1844. Proto- 

 medea, G. 0. Costa, 1861 (in part). Embolus, Jeffreys, 1869. 



Animal with an indistinctly defined head, which is only marked 

 externally by the lips on the border of the mouth and by the tentacles. 

 Fins elongated, enlarged, truncated at their free end. 



Shell umbilicate, with turns gradually increasing ; with a fairly 

 large aperture, and with a columera not prolonged into a rostrum ; 

 surface, smooth or striated. The height of the spire, the form of the 

 surface and that of the aperture, and the size of the umbilicus vary 

 according to the species. Operculum semilunar, with a right-handed 

 spiral of a few whorls. 



1. Limacina australis, Eydoux and Souleyet, 1840. Plate 6, fig. 7. 



Spirialis australis, E. & S., Revue Zool., iii, 1840, 237. Limacina australia, 

 E. & S. : Pelseneer, Chall. Rep., xxiii, 25. pi. 1, f. G ; Iredale, T.N.Z.I.. 

 xl, 384. 



Shell smooth, milky-white, the spire- somewhat elevated with a 

 blunted or obtuse apex, with 6 or 7 bulging whorls, separated by a 

 very deep suture, with the last whorl much expanded and convex, 

 and projecting more in proportion than all the foregoing. Aperture 

 quadrangular, somewhat angled in front ; columella"straight, reflected 

 to the right ; umbilicus broad. Operculum approximately oval, with 

 an almost straight columellar margin, and with a spiral portion 

 measuring barely two-fifths of the entire length. 



Diameter, maj.. 1-5 mm. ; height, 2-2-5 mm. 



