330 KOBEN AND DANIELSSEN ON THE 



Article XI. 



Observations on the Development of the Pectinibranchiata. 

 By MM. KoREN and Danielssen. 



[From the Annates des Sciences Naturelles, t. xviii. No. 5, and t. xix.] 

 ^ \. On the Development of Buccinum undatum, Linn. 



Although, since we first made known our investigations 

 into the development of the MoUusca, in the Magazin for 

 Naturvidenskaberne, many remarkable memoirs have appeared 

 upon the same subject (those of Nordmann*, of Vogtf? of Qua- 

 trefages J, of Loven§, of Reid ||, and of Leydig^f), yet we think 

 it advisable to set forth our observations here in full, and we 

 trust that they will not be read without interest — particularly 

 as we have been able, in two genera of Gasteropods, to follow 

 step by step the development of the embryo from its first 

 appearance to its complete formation, and as we shall have to 

 bring forward facts new to science. 



On the 1st of March, 1851, we procured many oviparous 

 capsules of Buccinum undatum. It is well known that these 

 capsules, spherical or ovoid in form, are most usually found united 

 into racemes nearly as large as the fist. They are attached to 

 various bodies, such as rocks, bits of old wood, marine plants, 

 &c. In many of these racemes, the capsules contained incom- 

 plete young, in others ova. We possessed then all the materials 

 required for our researches. To judge from the internal condition 



* Versuch einer Monographic von Tergipes Edwardsii. 



f Recherches sur VEmhryogenie de V Action {Annates des Sciences Naturelles, 

 3rd ser. t. vi. 1846, p. 1). 



X Arenales des Sciences Naturelles, 3rd s6r, t. iv. p. 33. 



§ Bitrag til Koennedomen om Utwecklingen af Mollusca Acephala lamelli- 

 hranchiata (Kongl. Vet. AJcad. Handl. 1848). 



II Ueber die Entwickelung der Eier der Mollusca nudihranchiata (Froriep's 

 Jahresherichte, Januar 1850). 



^ Ueher Paludina vivipara {Zeitschrift fur wissenschaftliche Zoologie. 

 Leipzig, 1850). 



