Mollusca. 103 



sal surfaces of tlie gill filaments. It enters the mantle cavity on the left in the 

 front, passes between the gill filaments and out at front on the right. 



I. On entering the inhalent Chamber the velocity of the food current falls 

 and the heavy particles drop to the fioor. They are caught by a forwardly 

 directed stream caused by cilia on the animals head and neck, and the border 

 of the mantle and directed into a pouch on the right hand side of the head (the 

 food pouch). When a sufficient amount of food has been accumulated here it 

 is seized and drawn into the mouth in the manner described below. If this food 

 current contains grains of sand, etc. the entrance to the food pouch may be 

 closed and the offensive particles rejected. 



IL The gill Stretches across the mantle cavity and separates the lower in- 

 halent from the upper exhalent cavity. On Coming into contact with the gill the 

 s mall er particles (which have been separated from the heavier particles as 

 above) are entangled in mucus secreted by the gill and swept by cilia on the ven- 

 tral and dorsal faces of the filaments towards their tips and dei^osited in a ciliated 

 groove (food groove) which runs forward to the mouth. Here the food is mixed 

 with mucus to form a cylindrical mass which is passed forward to the mouth at 

 intervals. It is seized and drawn into the mouth by the radula and retained by 

 the mandibles. 



A description of the method of feeding in Östren, Mytilus, Cardium and 

 Pecien is given. It is shown that in Lamellibranchs as well as Crcpidida the 

 main food and respiratory current is caused by the lateral cilia on the gill filaments 

 while the collection and tranportation of the food is effected by the frontal cilia 

 of the filaments. 



The gill filaments of Nucnla possess similar cilia with a similar function to 

 those in the gills of higher Lamellibranchs. In Nacula nucleus there are even 

 ciliated discs interlocking adjacent leaflets. It is also shown that the gill in 

 Nucula divides the mantle cavity into an upper and lower branchial Chamber and 

 that the ventral surface of the gill is used for food collection. The gill of Nu- 

 cula is thus essentially similar to that of some Filibranchs (e. g. Änomia and 

 Dimya) and in the opinion of the author, the Protobranchia caunot be maintained 

 as a group coequal with the Filibranchiata but only as a subdivision of that group. 



Most Gastropods have gill filaments essentially similar in structure and func- 

 tion to those of Lamellibranchs, the lateral cilia producing the main current and 

 the frontal collecting food particles. It seems probable that all these forms must 

 feed partly on plancton. Potts (Cambridge). 



313) Eliot, Sir Charles, A note on the rare British Nudibranch Hancockia 

 eadactylota Gosse. In: Proc. Zool. Soc, London, S. 770, Taf. LXXXV, 1912. 



314) Kobelt, W., Landschnecken aus Deutsch-Ostafrika und Uganda- 

 In: Revue Suisse ZooL, Bd. 21, S. 57—74, Taf. 2, 1913, 



Carls kleine Landschnecken- Ausbeute im Westen und Norden vom Victoria- 

 See enthielt lauter neue Arten und Varietäten. Kobelt beschreibt: Ennea caroli, 

 Helicarion caroli, Martensia busaensis, Pseudoglessula (?) xissuwiensis , P. ptychaxis 

 E. Sm. var., Subulina victoriae, sowie sechs neue Arten von Limicolaria. Letztere 

 bilden den interessantesten Bestandteil der Sammlung. Sie bestätigen wiederum die 

 große geographische und individuelle Varietät der Limicolarien und bestärken den 

 Verf. in seiner schon früher ausgesprochenen Ansicht, daß die nächste Aufgabe 

 die Aufstellung von Formenkreisen sei und daß die bisherige Artunterscheidung, 

 bei der der Zeichnungscharakter die Hauptrolle spielte, aufgegeben werden müsse 



