10 COPE 



Respiration pharyngeal; no external bran- 

 chiae ; alimentary canal straight, travers- 

 ing the body lengthwise ; Enteropneusta. 



Respiration wholly or in part performed by 

 external branching processes; alimen- 

 tary canal bent upon itself, anus at oral 

 extremity ; Lophopneusta. 



The order of Enteropneusta includes but one family, 

 the Balanoglossidse, which consists of animals of worm- 

 like form, which burrow in the soil of the seacoasts of 

 most continents between high and low tide. They have a 

 larva resembling that of the Echinoderma. 



The order of Lophopneusta includes sessile, and so far 

 as yet known, compound forms, which inhabit the ocean 

 bed, attached to solid substances. There are two families, 

 the Cephalodiscidee with gill-slits, and the Rhabdopleuridse 

 in which gill-slits are wanting. 



No extinct forms of Helminthophya are known. 



Superclass II.— UROCHORDA. 



There is but one class of Urochorda : 



Not metameric ; a mantle covering the body ; 

 respiration pharyngeal ; heart distinct, 

 saccular ; Tunicata. 



Class I.— TUNICATA. 



There are three orders of Tunicata as follows : 



Cloaca posterior ; caudal appendage per- 

 sistent. Individuals simple, free ; Perennichordata. 



Cloaca posterior; caudal appendage ab- 

 sent or caducous ; protostigmata un- 



