LIMACINIDAE 281 



The above were taken north of Tristan da Cunha and between that island and Cape 

 Town. They measured 7-1 1 mm. in length. This species is abundant in the warm waters 

 of the Atlantic, Indian and Pacific Oceans. Boas (1886, p. 131) explains why the name 

 Cuvieria, given by Rang, cannot be used. The genus is characterized by having a body 

 which is rounded posteriorly. The cephalic lobe is rudimentary. The right tentacle is 

 much longer than the left. The radula has a median tooth with an almost rectangular 

 base, with a breadth twice its length. The cusp, dentate only on the upper sides which 

 slope towards the anterior corners of the base, is much more powerful than in the two 

 species last mentioned. The lateral teeth are much smaller in proportion and have very 

 short cusps with denticles varying in number from about seven to seventeen. The apron 

 is broad, but so narrow as to show the mouth. The shell is at first cylindrical and termin- 

 ates in a point. The pointed portion is separated from the rest of the shell by a partition : 

 it is easily broken oft", but, when perfect, forms one-third of the length of the shell. The 

 latter is transparent and finely striated both longitudinally and transversely. The widest 

 part is about at the centre of a complete shell, instead of being at the mouth as in Cleo- 

 dora. Just below the mouth the shell is slightly constricted and, as the under-side is 

 somewhat hollowed out anteriorly, it follows that the mouth is kidney-shaped rather 

 than circular. 



C. urceolaris, Morch, is regarded by Boas and Vayssiere as a variety of C. columnella. 

 It is found in the Pacific and is characterized by having a smaller shell which is more 

 swollen posteriorly and less drawn out anteriorly, and the neck is scarcely indicated. 



Vayssiere (191 5, p. 107) mentions having examined specimens from New Caledonia 

 and found their organization to be similar to that of the typical variety of the Atlantic. 



Family LIMACINIDAE 



Genus Limacina, Cuvier, 18 17 



Limacina helicina (Phipps), 1773. 



Argonaiita arctica, O. Fabr., 1780. 



Limacina arctica, Moller, 1841. 



Limacina antarctica, Woodward, 1856; Pelseneer, 1887; Eliot, 1907. 



Extremely numerous in the seas surrounding South Georgia and the South Sandwich Islands. 

 No fewer than 5706 specimens were collected at seventy-eight stations in this area. 



All the specimens were taken during the Antarctic summer, two-thirds of the hauls 

 being made in December and January. The largest shoals were taken at South Georgia, 

 and at night. On one occasion (St. 136) 2074 specimens, measuring 3-5 mm., were caught. 

 In all cases the measurements are those of the diameter of the body coiled up, and not 

 with fins extended. The diameter varied from i to 6 mm. Most of the specimens had 

 lost their shells, and opercula were usually present only in very young individuals. One 

 example of 3 mm. diameter was, however, observed with an operculum. This is oval, 

 with only one turn in the spire. A small gelatinous mass was taken in a December haul, 

 at the South Sandwich Islands (St. SS 31), which contained a number of vertical white 



