654 CHORDATA 



by a separate pore. The sexes often differ from each other in color. 

 The development is a metamorphosis, the characteristic larva, which is 

 called the tomaria, resembling the larvae of the echinoderms in form 

 and structure. This larva is not present, however, in Balanoglossus 

 aurantiacus, one of the most familiar American forms. 



The American Balanoglossida live mostly in shallow water, in the 

 sand and mud, in which they burrow with aid of the proboscis. The 

 animals leave a coiled mass of sand held together by mucous on the 

 surface of the sand, which indicates the presence of the burrow ; they also 

 give out a disagreeable odor. They were first described by Eschscholtz in 

 1825, who put them in the genus Ptychodera, while Delle Chiaje in 1829 

 gave them the generic name Balanoglossus, which has been the familiar 

 name of the animals ever since. About 25 species are known, which are 

 grouped in 4 families. 



Key to the American families of Balanoglossida: 



Oy Liver sacs present 1. Ptychodemdae 



Oa Liver sacs absent 2. Habbimaniidae 



Family 1. PTYCHODERIDAE. 



Paired liver sacs present behind the gill slits; chitinous rods sup- 

 porting the gill arches joined by connecting bars (synapticula) ; central 

 nervous system with nerve roots: 3 genera. 



1. Ptychodera Eschscholtz. Gill openings to outside are long 

 slits; a pair of longitudinal dorsal wing-like lobes (genital wings) 

 present in the genital region: 10 species. 



P. biminiensis Willey. Body large and finger-thick; proboscis 

 short: Bahamas. 



2. Balanoglossus Delle Chiaje. Gill openings to outside are small 

 pores; proboscis short, with paired pores; medial gonads present: 5 

 species. 



B. aurantiacus (Girard) {B. hrooksii Bateson). Length 15 cm. or 

 more, sometimes a meter; color bright purplish or greenish: North and 

 South Carolina. 



B. jamaicensis Willey. Body large, with transverse red bands: 

 Jazpaica. 



Family 2. HARRIMANIIDAE. 



Liver sacs, synapticula, and nerve roots absent: 2 genera. 



1. DoLlCHOGLOSSxrs Spengel. Proboscis long and with but one pore; 



