416 



species are described and arranged in the family Litorinidce, between 

 Turritella and Chemnitzia. According to the mode of diagnosis 

 here adopted, five of these species are resolvable into one. The types 

 are in the Amherst College Museum ; but duplicate types of six were 

 sent by the author to Mr. Cuming, and have supplied what was 

 wanting in the descriptions. Prof. Adams recorded that he had 

 found several species at Jamaica ; but he did not describe them. 



In Woodward's valuable ' Manual of Mollusca,' 1851, p. 133, the 

 then accessible knowledge was condensed, and the genus placed in 

 Turritellidce, between Aclis and Vermetus. 



In Dr. Gray's « List of Genera," P. Z. S. 1847, p. 203, no. 775, 

 " 1 Ccecum " appears with its synomymy in Family Cleodoridce 

 (Pteropoda*). In the 'Fig. Moll. An.' p. 85, the group first appears 

 as a family, between Scalariadce and Truncatellidce. In the ' Guide 

 Syst. Distr. Moll.' 1857, part i. pp. 100, 101, the family is placed 

 between Bissoidce and Melaniadce, and the genus Brochina is insti- 

 tuted. 



In Messrs. H. and A. Adams's ' Genera of Recent Mollusca,' now 

 publishing, vol. i. p. 355, the family Ccecidce is placed betwen Tur- 

 ritellidce and Vermetidce. In Philippi's • Handb. Conch. & Mai.' 

 p. 197, the Ccecacea appear as a family between Vermetacea and 

 Siphonariacea. 



The naturalists of France do not appear to have been acquainted 

 with these shells till of late years ; neither in the works of Lamarck, 

 Cuvier, Sander Rang, D'Orbigny, nor Deshayes, is there to be found 

 any notice of their existence. This is the more remarkable, as 

 D'Orbigny paid no little attention to the minute shells of the West 

 Indies and South America. It is true that Chenu has copied Brown's 

 figures of Cornuoides major and Brochus " troeehiformis" in his 

 'Illustr. Conch.' ; but it is hardly possible to recognize even the genus 

 in them. 



In the 'B.M. Cat. Maz. Moll.' pp. 312-329, were described, in 

 August and September 1856, eighteen species of Ccecum, grouped 

 under three heads according to sculpture, viz. Elephantulum, Anellum, 

 and Fartulum. At the same time I prepared descriptions of the 

 remaining foreign species. The whole have now been subjected to 

 a rigid examination, after the study of about 1000 additional speci- 

 mens, principally from Mazatlan, the West Indies, and Teneriffe. The 

 best series of types of all the species at my disposal I have presented 

 to the British Museum. These will aid future students in correct- 

 ing the errors into which I have doubtless fallen, not from want of 

 patient care, but of materials and judgment. Other series of types 

 are prepared for public museums in America and on the Continent. 



Station and Geographical Distribution. 



The established European species are only two in number — Ccecum 

 trachea and Brochina glabra ; but these have been found from Scot- 

 land to the Mediterranean. The living specimens have been taken 



* See ' B.M. Cat. Pteropoda,' p. 3, no. 7, where the error is corrected. 



