LIMACINIDAE 283 



(6) Variations in the teeth. Sir C. Eliot found the base of the median tooth in L. ant- 

 arctica to be straight, while in L. helicina it was almost horse-shoe shaped. I have found 

 that this character is dependent upon the position which the tooth happens to take when 

 being mounted. Even in the same specimen the median tooth can exhibit both these 

 forms. 



Distribution. Coasts of Norway (Sars, 1878). Spitsbergen (Vayssiere, 1915). Nova 

 Zembla, White Sea (Meisenheimer, 1905). Greenland, Iceland, Labrador; North 

 Pacific to California as L. pacifica, Dall (Boas, 1886, p. 42). In southern regions, where 

 Vayssiere (1915, p. 124) thinks it has been accidentally introduced by marine currents, 

 it has been observed as far north as 35° to 31° S (Meisenheimer, 1905). 



Limacina balea, Moller, 1841. 



Spirialis Gouldii, Stimpson, 1851. 

 Heterofiisiis balea, Mdrch, 1857; Gould, 1870. 



237 specimens identified with certainty, and 16 which appear to belong to this species, from 

 stations in the neighbourhood of South Georgia and the South Sandwich Islands. 



This species was taken in practically the same area as L. helicina, namely, the water 

 enclosing South Georgia, and the South Sandwich Islands, roughly from 52° S to 62° S 

 latitude, and from 20° W to 40° W longitude. Two very small specimens were taken a 

 few degrees further north (St. 11). The largest specimens have a spire of five or six 

 whorls. In all the spire is higher in proportion to the width of the last whorl than is the 

 case in L. retroversa (Fleming). Spiral striae were not observed on any of the shells. The 

 specimens were usually taken in small numbers, but in four hauls made at the end of 

 May 1927 off Cumberland Bay, South Georgia, catches of fifty to two hundred occurred. 

 The other hauls were made from November to March. Boas (1886, p. 44) states that his 

 largest specimen measured 5-5 mm. in length and the shell had ten whorls. It was finely 

 striated spirally and transversely. Boas {op. cit.) and Vayssiere (1915, p. 143) regard 

 L. retroversa (Fleming) as the same species as L. balea and consider that the various 

 differences noted in the shell are due to differences of age. In support of this view I may 

 mention that all the specimens I have seen of L. retroversa are smaller than L. balea. On 

 the other hand, both in the present collection and in that made by the ' Terra Nova ', the 

 two forms were not taken together. The localities were indeed widely separated. 



Distribution. Temperate zones between Arctic and Antarctic and circumtropical 

 zone (Bonnevie, 1913). 



Limacina retroversa (Fleming), 1828. 



Heterofitsus retroversus, Fleming, 1828; Gould, 1870. 

 Atlanta trochiformis, d'Orb., 1835-47. 

 Spinalis flemingii, Forbes and Hanley, 1850. 



Two specimens were picked out from a haul north-east of the Falkland Islands (St. 68). 

 Distribution. Atlantic and Pacific in warm and temperate seas (Bonnevie, 1913). 

 Mediterranean, British Isles, and occasionally off Norway (Sars, 1878). 



