MUSEUM OF COMPARATIVE ZOOLOGY. 49 



thin, arched forward in the middle ; pillar thin, simple, with no trace of a 

 plait; body without perceptible callus; behind the pillar a small, very deep 

 umbilical perforation ; apex nearly fiat, bounded by the above-mentioned raised 

 line, within which the fasciole of the notch is rounded over but does not reach 

 the level of the line referred to ; nucleus somewhat depressed, but not deeply ; 

 about three and a half whorls are visible on the apex. Max. Ion. of shell, 

 4.0 ; max. lat. of do., 2.5 ; lat. of apex, 1.5 mm. 



Habitat. West Indies, U. S. Fish Commission, probably from near Barba- 

 dos, in about 80 fms., sand. 



This species is remarkable for its deep though minute umbilicus and it- 

 dish-like apex. Its general form is not unlike U. perplicatus, but the sides 

 are straighter and the other characters quite different. The locality is unfor- 

 tunately doubtful, though it was somewhere in the Antilles. 



Subgenus RETUSA (Brown) Morch. 

 Retusa ? OVata Jeffreys. 



Cylickna ovata Jeffreys, Rep. Brit. Assoc, 1870, Pore. Exp., p. 156. Ann. Mag. 



Nat. Hist., 5th ser., X. p. 34, 1882. Watson, Chall. Rep., p. 664, pi. xlix. fig. 



9, 1885. 

 Utriculus conulus G. 0. Sars, Moll. Reg. Arct. Norv., p. 287, pi. 17, fig. 17, 1878. 

 Cylichna umbilicata var. conulus Jeffr., Brit. Condi., IV. p. 414 ; V. p. 223. 

 Not Bulla conulus Deshayes, Cylichna conulus of Weinkauff, or Bulla conulus of 



Searles Wood. 



Habitat. North Atlantic, Porcupine and Triton Expeditions; Bay of Bis- 

 cay, Travailleur Expedition; Azores, Josephine, Porcupine, and Challenger 

 Expeditions ; West Indies, off Culebra Island, Challenger Expedition ; off Per- 

 nambuco, Challenger Expedition; Straits of Florida, 150-465 fms., Dr. Rush; 

 east coast of North America, 124-400 fms., U. S. Fish Commission. Range 

 100-1000 fms. over a muddy bottom in all parts of the North Atlantic, with 

 temperatures from 40°.0 to 62°.0 F. 



Retusa ? obesiuscula Brcgnone. 



Cylichna obesiuscula Brugnone, Bull. Soc. Mai. Ital., III. p. 39, pi. i. fig. 7, 1877. 

 Diaphana conulus Verrill, Proc. U. S. Nat. Mus., HI. p. 382, 1880 ; Trans. Conn 

 Acad., V. p. 543, pi. lviii. fig. 25, 1882; VI. p. 273, 1884. 



Habitat. Pliocene of Messina, Seguenza ; of Palermo, Brugnone. U. S 

 Fish Commission Stations 870, 949, 2595, 2602, and 2614, in 63-168 fms 

 living in about 100 fms., temperature 61° F., over a sandy bottom. 



This species is quite distinct from Bulla conica or conulus of Deshayes, Wood, 

 Sars, etc., from C. Hcernesi and C. ovata, with all of which it has been con- 

 founded by various authors, especially Jeffreys. Professor Verrill in referring 

 to it noted the discrepancies. 



VOL. xviii. 4 



