ArPENDICULARlA. 609 



The structure of the branchioo of this Ascidian, and the 

 position of the two orifices, as observed by Huxley, indicate 

 a position for Doliolum intermediate between Salpa and 

 Pyrosoma. The animal progresses by contracting the 

 whole body and forcing the water out at one or the other 

 extremity. 



Species of Doliolum. 



denticulatum, Quoy and Gaim. Nordrnanni, Krohn. 

 Miilleri, Krohn. Troschelii, Krohn. 



Genus APPENDICULARIA, Chamisso. 



Body flask- shaped, with a lanceolate appendage ; mouth 

 at the bottom of the respiratory cavity; respiratory orifice 

 at the smaller extremity ; branchiae represented by a ciliated 

 band of the inner tunic ; anus on the dorsal surface in 

 front of the insertion of the caudal appendage. 



Syn. Oikopleura, Mertens. Fretillaria, Quoy and Gaim. 

 Vexillaria, Midler. 



Ex. A. flagellum, Chamisso, pi. 136, fig. 5. 



This curious genus, first discovered by Chamisso, near 

 Bearing's Straits, afterwards more fully described by Mer- 

 tens, and observed in immense masses by Quoy and Gaim- 

 ard, has been ably investigated by Huxley in the Philoso- 

 phical Transactions, who has first shown the true relations 

 of the animal, and its position among the Tunicated Mol- 

 lusca. They would appear to typify, in their adult state, 

 the larval condition of the higher Ascidians. The animal 

 is rapidly propelled through the water by powerful vibra- 

 tions of the long, curved, caudal lanceolate appendage. 



