258 Proceedings of the Eoyal Physical Society. 



1884. Perothis JDussumieri, Rochebr., Monogr. Loligopsidse, p. 28. 



1885. Leachia cyclura, Hoyle, Loligopsis, p. 326. 

 Atlantic, Indian, and Pacific Oceans. 



2. L. ellipsoptera (Ad. and Ev.), Stp. 



1848. Loligo])sis ellipsoptera, Ad. and Rv., Yoy. " Samaraiig," Moll., 



p. 2. 

 1861. Leachia ,, Stp., Overblik, p. 80. 



1884. Dyctydiopsis ,, Rochebr., Monogr. Loligopsidse, p. 18. 



1885. Leachia ,, Hoyle, Loligopsis, p. 328. 

 Atlantic Ocean. 



3. L. dubia (Rathke), Hoyle. 



1833. Perothis chibia, Rathke, Mem. Savans Strang. St. Petersb., ii., 



p. 170. 

 1885. Leachia ,, Hoyle, Loligopsis, p. 329. 

 Indian Ocean. 



Loligopsis/ Lamarck, 1812. 



Loligopsis, Auctt. (pars). 



1. L. Peronii, Lmk., Extrait de son Cours de Zool., p. 123, 1812 



(Jlde d'Orb.). 

 1861. Loligopsis Peronii, Stp., Overblik, p. 85. 

 1885. ,, ,, Hoyle, Loligopsis, p. 314. 



Pacific Ocean (?). 



2. L. zygaena, Yer., Ceph. medit., p. 125, pi. xl., fig. c, 1851.^ 



1884. Zygcenopsis zygoma, Rochebr., Monogr. Loligopsidse, p. 20. 



1885. (?) ,, Hoyle, Loligopsis, p. 331. 



Mediterranean Region. 



Order IL TETRABRANCHIATA, Owen, 1832. 



Family XIV. Nautilid^, Owen, 1836. 



Nautilus,^ Linnd, 1757. 



1. N. pompilius, Linn., Syst. Nat., ed. xii., p. 1161, 1766. 



1868. Nautilus pompilius, Kiister, Conch. Cab., sec. 55, p. 9, pi. 2, 

 fig. 2. 



1 The true position of this genus is entirely uncertain : the description of 

 the type species, based upon a drawing, is so fragmentary, that nothing can 

 be extracted from it as to the affinities of the animal. See also note, p. 229. 



2 This is certainly not a Loligopsis in the Lamarckian sense, but at present 

 there is no ground for referring it to any known genus whatever, nor do I 

 think its characters sufficiently well known to enable a new genus to be 

 erected for it ; I therefore leave it as placed by the original describer. The 

 name proposed by de Rochebrune is preoccupied. 



2 Having no sufficient personal knowledge of the different species of this 

 genus, I have followed Kiister (Zoc. cit.) in their enumeration; what study I 

 have had the opportunity of giving them leads me to think that they may, 

 perhaps, be reducible to two species. Nautilus pompilius, Linn. , and Nautilus 

 umlilicatus, Lister, with a number of more or less well marked varieties. 



