44 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
circumference is circular, while the mature stage is more or less flattened. The 
figure of d'Orbigny exhibits a young stage or pygmy form with circular basis, 
and resembles in all respects our form in its young state. 
Brady in Chall. Rep. has apparently confounded two different forms under 
T. trochus of d'Orb. In Plate XLIII., Figures 15-19 should be assigned 
to T. conica D'OrB.; and in Plate XLIV., Figures 1-3 to T. trochus D'ORB., 
to which 7. Baretti, Figures 6-8, also belongs. 
T. trochus attains in the Caribbean Sea stout dimensions. 
Caribbean Sea. 262-400 fathoms ; not scarce. 
BIGENERINA v’Ors. 
B. capreolus D'ORB. 
Vulvulina capreolus n'Onn., 1826, Tab. Méth., An. Sc. Nat., VII. p 264, Pl. XI. Figs. 
5-8, Mod. 59. 
B. capreolus BR., 1884, Chall. Rep., IX. p. 372, Pl. XLV. Figs. 1-4. 
Caribbean Sea. 399 fathoms; very rare, 
ALLIED FORM : 一 
B. pennatula Barson. 
Nautilus pennatula Barscn, 1791, Conchyl. Seesands, Pl. IV. Fig. 13. 
Vulvul. elegans D’Ore., 1826, Tab. Méth., An. Sc. Nat., VII. p. 264. 
B. pennatula Br., 1884, Chall. Rep., IX. p. 373, Pl. XLV. Figs. 5-8. 
Is to be considered as a more advanced stage of the preceding. 
Caribbean Sea. 399 fathoms ; scarce. 
B. nodosaria D'Or». 
B. nodosaria D'ORB., 1826, Tab. Méth., An. Sc. Nat., VII. p. 261, Pl. XI. Figs. 9-11, 
Mod. 57. 
B. agglutinans D'ORB., 1846, Bass. tert. Vienne, p. 238, Pl. XIV. Figs. 8-10. 
Text. sagittula var. Gois, 1882, Ret. Rhiz. Caribb. Sea, Sv. Vet. Ak. Hdl., XIX. 4, 
Pl. V. Figs. 133-139. 
B. nodosaria BR., 1884, Chall. Rep., IX. p. 369, Pl. XLIV. Figs. 14-18. 
B. nodosaria Goüs, 1874, Arct. & Scand. Foramf., Sv. Vet. Ak. Hdl., XXV. 9, p. 87, 
Pl. VII. Figs. 313-323. 
Ts not met with in the “ Albatross” dredgings, but attains in the Caribbean 
Sea a high development, although it is of rare occurrence. 
Caribbean Sea. 300 fathoms (Goés). 
