MANUAL OF NATURAL HISTORY. 167 



2. Diademnince. Body distinctly divided into 

 two parts, thorax and abdomen. 



8. Botryllinoe. Body not divided into a dis- 

 tinct thorax and abdomen, the viscera being 

 pushed forward on side of branchial cavity 

 and forming, with thorax, an ovoid mass. 



4. Family. — Pyrosomes (Pyrosomatidse). Common 



body semi-cartilaginous, floating, cylindrical, 

 open at one of its extremities only ; animals 

 associated in a verticillate arrangement, hav- 

 ing two orifices one at each extremity. 



5. Family. — Salpians (Salpidse). Animal free, pela- 



gian, in form of a more or less cylindrical 

 tube open at one or both ends ; test and 

 mantle continuous at respiratory aperture, 

 but elsewhere separated by a wide space ; 

 gill forming a hollow band across respiratory 

 cavity ; anal orifice ending close above and 

 to right side of mouth. 



6. Family. — Pelonaians (Pelonaiidse). Body cylin- 



drical, with the branchial and anal orifices 

 on the same plane on papillary eminences 

 at one extremity ; no rays or tentacles sur- 

 rounding either of the 4-cleffc orifices. 



7. Family. — Appendicularians (Appendiculariidse), 



Body flask-shaped, with a lanceolate append- 

 age ; mouth at bottom of respiratory cavity ; 

 respiratory orifice at smaller extremity ; gills 

 represented by a ciliated band of mantle ; 

 anus on dorsal surface, in front of insertion of 

 caudal appendage. 



