20 
THE VOYAGE OF H.M.S. CHALLENGER. 
hesitation the same author 1 also unites Bellerophon minuta, Forbes, 2 with the present 
species. But the perfect bilateral symmetry of this very minute shell makes it more 
probable that it is only a young Oxy gyrus keraudreni (Heteropod). 
*2. Limacina triacantha (Fischer) (PI. I. figs. 1, 2). 
1882. Embolus triacanthus , Fischer, Diagnoses d’especes nouvelles de Mollusques recueillis 
dans le cours de l’Expedition scientifique de l’aviso le Travailleur 
(1880, 1881), Journ. de Conchyl., t. xxx. p. 49. 
Characters and Description. — Smooth globular shell, flattened above. Spire very 
short. Three whorls, expanded and overlapping, lying almost in the same plane as in 
the preceding species. Suture well marked. Mouth large and widened ; lip with three 
teeth, one above almost on the suture, one inferior, and the third on the lower half on 
the face of the longer portion of the curve. The two last teeth are the largest, and 
with each tooth there corresponds a longitudinal rib, somewhat narrow and projecting, 
parallel to the axis of the shell. The two superior ribs do not extend over the whole of 
the last coil. Straight columella. Narrow umbilicus. Colour w T hitish, the three ribs 
brown. 
Dimensions. — The maximum diameter and height of the shell are almost equal, and 
measure 4|- mm. in the larger specimens. 
The animal and the operculum are unknown. 
Habitat. — Atlantic Ocean, to the south of Spain, at a depth of 1205 metres. 
Challenger Specimens. — Deposit shells. 
Station 23, March 15, 1873 ; off Sombrero Island; lat. 18° 24' N., long. 63° 28' W.; 
depth, 450 fathoms ; bottom, Pteropod ooze. 
Station 24, March 25, 1873 ; off Culebra Island ; lat 18° 38' 30" N., long. 65° 5' 30" 
W.; depth, 390 fathoms; bottom, Pteropod ooze. 
Station 33, April 4, 1873 ; off Bermuda; lat. 32° 21' 30" N., long. 64° 35' 55" W.; 
depth, 435 fathoms ; bottom, coral mud. 
Station 76, July 3, 1873; off the Azores; lat. 38° 11' N., long. 27° 9' W.; depth, 
900 fathoms ; bottom, Pteropod ooze. 
Station 85, July 19, 1873 ; off Palma Island ; lat. 28° 42' N., long. 18° 6' W.; depth, 
1125 fathoms; bottom, volcanic mud. 
Observations . — It is quite likely that Embolus elatus, Seguenza 3 (not Protomedea elata, 
Costa), from the Sicilian Pliocene is identical with the above species. The diagnosis, 4 
1 On Mediterranean Mollusca, Ann. and Mag. Nat. Hist., ser. 4, vol. vi. p. 86. 
3 Report on the Mollusca and Radiata of the iEgean Sea, &c., Rep. Brit. Assoc., p. 186, 1843. 
3 Studii stratigraphici sulla formazione pliocenica, Bull, del R. Gomit. geol., fasc. 5, 6, p. 148, 1875. 
4 Studii paleontologici sulla fauna malacologica dei sedimenti pliocenici depositati a grandi profondita, p. 31. 
