SIR C. ELIOT. 



LiMACiNA RETROVERSA, Fleming. 



See especially Meisenheimer on Limacina retroversa, SMpolar Expedition (1906), IX. Band, Zool. I. Band, 

 Heft II., pp. 103-105 ; Eydoux and Souleyet on Spirialis australis, Eevue Zool. (1840), p. 237, and 

 Bonite (1852), p. '222 ; Pelseneer, 'Challenger' Eeport, LXV., pp. 25-27; Munthe, Pteropoder, 

 pp. 8, 9 (1887). 



There are six tubes containing specimens of a whitish Limacina of small or 

 moderate size, with a spire of somewhat varying height, but never so low as that of 

 L. helicina or L. antarctica. The labels are : — 



1. Lat. 55° 44' S. Long. 95° 43' 30" W. 5 fathoms (11 spec). 



2. Lat. 56° 12' 45" S. Long. 136° 18' 30" W. 10 fathoms (3 spec). 



3. Lat. 57° 25' S. Long. 151° f E. (Several spec) 



4. Lat. 59° 19' S. Long. 120° 24' 30" W. 5 ms. (6 spec). 



5. Lat. 59° 34' S. Long. 106° 28' 13" W. 5 fathoms (4 spec). 



6. Lat. 61° 13' 30" S. Long. 173° 33' E. (Several spec) 



The tubes contain comparatively few specimens, and suggest that this species is 

 not found in abundant shoals. 



The shells show considerable variation in form (fig. 7). No differences were 

 found in the animals, though, as they were without exception retracted into 

 their shells, the investigation of the foot and fins was difiicult. An accessory lobe 

 was, however, found on all the fins which could be extended, and after examining 

 numerous specimens of L. retroversa from the coast of Scotland, I can confirm 

 Meisenheimer's statement (Siidpolar Exped., p. 104) that the lobe occurs in this 

 northern form. The radula appears to be much the same in all specimens, and 

 substantially as in L. retroversa. 



The shell varies in colour from greyish white to yellowish brown, but is always 

 rather opaque, not striated, but covered with fine granulations arranged in no apparent 

 order. The height of the spire varies from 1 mill, to 2 mill., the latter dimensions 

 being rare, and the maximum breadth across the last whorl is 1 mill. The umbilicus 

 does not vary materially in shape ; it is distinct, straight, rather narrow, and 

 I did not find the distinction in breadth mentioned by Prof. Pelseneer ('Challenger' 

 Eeports LXV., pp. 26 and 27). The mouth is subquadrangular. 



The variation in the shape of the shell produces two types. Type A (fig. 7a) 

 is tall, with very deep sutures and six or seven whorls, which increase symmetrically 

 in size, the last not being disproportionately large. In many of these shells, as 

 preserved, the columella is not continued at the side of the mouth. Type B (fig. 7c) 

 is smaller and lower ; the sutures are not so deep ; there are only four or five whorls, 

 and the last whorl is disproportionately large and swollen. 



