332 Proceedings of the Royal Physical Society. 



genus Zygcenopsis, but, even were tliis procedure on other 

 grounds admissible, the fact that the name proposed is pre- 

 occupied is fatal. 



In concluding, I have to acknowledge my indebtedness to 

 Professor Steenstrup, both for the opportunity of examining 

 the collection of Cephalopods in the Copenhagen Museum 

 and for valuable advice and assistance during the progress 

 of my work, as well as to Dr de Eochebrune for the courtesy 

 with which he facilitated my examination of the valuable type 

 specimens in the Paris Museum — it is a source of great regret 

 to me that I find myself differing from him in so many points. 



List of Abbreviations Employed. 



d'Orl)., Ceph. Acet. 



Ferussac et d'Orbigny, ' ' Histoire natiirelle generale et particuliere des 

 Cephalopodes acetabuli feres." Paris, 1835-48. 

 d'Orb., Moll. viv. 



d'Orbigny, ''Mollusques vivauts et fossiles." Paris, 1845 & 1855. 

 Gray, B. M. C. Moll. 



Gray, J. E., "Catalogue of tlie Mollusca in the Collection of the 

 British Museum ; Part i., Cephalopoda Antepedia." London, 1849. 

 Pfeffer, Ceph. Hamb. Mus. 



"Die Cephalopoden des Hamburger Naturhistorischen Museums" — 

 Ahhandl. Naturwlss. Verein. Hamhurg, 1884. 

 Rochebr., Monogr. Loligopsidse. 



Dr de Rochebrune, "Etude monographique de la famille des Loli- 

 gopsidse" — Bull. Soc. Philom. Paris, ser. 7, t. viii., No. 1, 1884. 

 Steenstrup, Hectocotyldannelsen. 



*•' Hectocotyldannelsen hos Octopodslsegterne, Argonauta og Tremoc- 

 topus" — K. Danske VidensTc. Selsk. Skriv., Bd. iv,, pp. 185-216, 

 1856. (English Trans., Ann. and Mag. Nat. Hist., ser. 2, vol, xx., 

 pp. 81-114, 1857.) 

 Steenstrup, Overblik. 



" Overblik over de i Kjobenhavns Museer opbevarede Blfeksprutter 

 fra det aabne Hav" — Oversigt o. d. k. Danske Vidensk. Selsk. 

 Forhaiidl., 1861. 

 Tryon, Man. Conch. 



Tryon, G. W., jun., "Manual of Conchology, Structural and Syste- 

 matic," vol. i. Philadelphia, 1879. 

 Verany, Ceph. Medit. 



" Mollusques mediteraneens ; Partie i., Cephalopodes." Genoa, 1851. 

 Verrill, Ceph. N.E. Amer. 



" The Cephalopods of the North-Eastern Coast of America" — Bsjwrt 

 of the U.S. Commissioner of Fish and Fisheries for 1^1^. Washing- 

 ton, 1882. Also, Trans. Connect. Acad., vol. v., part 2, 1882. 



