found in the stomachs of certain Mollusca. 323 



Clam, &c. ; and Dr. Hooker in the ' Botany of the Antarctic Voy- 

 age ' states, that the stomachs of Salp(B and other (especially of 

 the naked) Mollusca invariably contain DiatomacecB, sometimes 

 several species. These Salpce were washed up in masses on the 

 pack ice, and in decay they left the snow covered with animal 

 matter impregnated as it were with Diatomacece. He found that 

 the contents of the stomach of every Salpa, between the latitudes 

 of the North Tropic and 80" South, invariably contained the re- 

 mains of these minute plants. Dictyocha aculeata was universally 

 observed in the stomachs of those found off Victoria Barrier. 

 Mr. Lee has found them abundant in the stomach of the com- 

 mon Barnacle. 



The following notes of species detected in the stomachs of 

 different species of Ascidia and of the freshwater Mussel {Mya 

 margaritifera, L.) may be worthy of record. They do not appear 

 to have the same discrimination as to their prey which the fishes 

 would seem to exercise, every object, whatever be its nature, 

 coming within the sphere of the currents produced by the cilia, 

 is swallowed, provided its size be not too great. The Ascidia 

 examined were from depths varying from twenty-five to thirty 

 fathoms, and five to six miles from land. 



A time was when there would have been some hesitation in 

 offering to the Society such a communication as the present, 

 owing to the conviction that some of the organisms to which it 

 has reference really belonged to the animal kingdom. The very 

 important discovery made by Mr. Thwaites, that they present 

 examples of conjugation like Zygnema, &c., leaves their true na- 

 ture no longer a doubtful question. There may still be some 

 dispute respecting the position occupied by such forms as Cosci- 

 nodiscuSj Actinoptychus, &c. ; but if it be admitted, and there 

 seems no reason for hesitation, that such genera as Meloseii'a and 

 its allies are true plants, it will not be difficult to understand also 

 the nature of those just mentioned, the transition from the one 

 to the other being obvious. 



Diatomacece found in the stomachs of different species of 

 Ascidia : — 



EunotiecE. Cocconoidets. 



Epithemia Sorex, A> ? Cocconeis Pedicuhis, Ehr. 



FragilariecE. Dorytthora amphiceros, Kg. 

 Fragilaria pectinalis, Ehr. 

 Diatoma flocculosum, Ag. Aclinanthea. 



Meloseirecp. Achnanthes longipes, Ag. 

 Meloseiva sulcata, Kg, Cymhellece. 



M. Jurgensii, Ag. ? Cymbella maculata, Kg. 



Surirellece. 

 Surirella? Gomphonemecs. 



Synedra laevis, Ehr. Gomphonema pohliaeforme, Kg. 



V 22* 



