Egllsii, Callostracnnrij Mesali?^ d-c. 367 



in the aperture and the operculum, which is paucispival, like 

 Littorina, and not mnltispiral, as in Turritella. 



The figures in Adams (Genera Recent Moll. vol. iii. 

 pi. xxxviii. figs. 4 a, 4 Z») represent the operculum of the 

 genus Turritella, and not that of Mesalia. 



This mistake led Dall * into the eiTor of stating that the 

 opercula ot" MesaHa and Tachyrhynchus [Mesalia reticulata) 

 ])resenfe(l no difference. The fact is, that of the former con- 

 sists of four or five rapidly eiilari^ing whorls with a somewhat 

 exceiitric nucleus, wiiereas that in the latter genus is multi- 

 .spiral, with central nucleus. 



The opercula of typical examples of M. hrevialis, from 

 Goree, in the British Museum, are almost black, rather con- 

 cave externally in the dried state, and consist of four or five 



Fi-. 2. 



rapidly increasing volutions, somewhat carinate at the suture 

 towards the deep nucleus, and with a raised spiral thread 

 upon them which does not extend to the last two large whorls. 



Mesalia hreviahs (Lamarck). 



1757. Cerithium mesal, Adanson, Hist. Nat. Senegal, p. xcv, Le Mesal, 



p. 159, pi. X. 

 1822. Turritella hrevialis, T.amarck, Anim. sans vert. vol. vii. p. 58. 

 184.3. Turritella hrevialis : Kiener, Coq. Viv. p. 40, pi. xii. tigs. 1, 1 a. 

 1843. Turritella mesal, Deshayes, Auiio. sans vert. ed. 2, vol. ix. 



p. 261. 

 1847. Mesalia mesal : Gray, Proc. Zool. Soc. 1847, p. 155. 

 1849. Mesalia hrevialis : Reeve, Conch. Icon. vol. v. pi. v. fig. 16 « 



( Turritella), fig. 2 b (Mesalia). 

 1852. Mesalia hrevialis : Sowerby, Conch. Man. ed. 4, p. 201, pi. xxviii. 



tig. 591. 

 1854. Mesalia hrevialis : H. & A. Adams, Gen. Rec. Moll. vol. i. p. 354, 



pi. xxxviii. fig. 4, shell (4 a, 4 b, represent the operculum of 



Turritella). 

 1857. Mesalia brernalis : Gray, Guide MoU. Brit. Mus. p. 111. 

 1859. Mesalia hrevialis : Chenu, Man, Conch, vol. i. p. 317, figs. 2284, 



2285. 



* Amer. Journ. Conch, vol. vii. p. 119. 



