142 CCELENTERATA 



Key to the families of Ilexactiniae here described: 



Gi Pedal disc absent ; usually sand dwellers 1. Halcampidae 



O2 Pedal disc present. 

 6, Acontia absent. 



Ci Body tuberculated 2. Bunodidae 



C2 Body not tuberculated 3. Paractidae 



bi Acontia present 4. Sagartiidae 



Family 1. HALCAMPIDAE. 



Pedal disc absent, the lower end being rounded or pointed and often 

 swollen; mesenteries few in number, 6 pairs of protocnemes with 4 

 to 6 pairs of metacnemes being present; no special sphincter; tentacles 

 12 to 36: about 6 genera. 



1. Halcampa Gosse. Body long and slender with longitudinal 

 grooves and composed of 3 sections, an oral retractile portion, an inter- 



Fig. 228 



Fig. 229 



Fig. 230 



Fig. 228 — Halcampa farinacea (from Parker). Fig. 229 — Bicidium parasiticum 

 (from Parker). Fig. 230 — Eloactis producta (from Parker). 



mediate portion usually coated with sand, and a pedal portion ; 2 siphono- 

 glyphs: several species, which live in sand and mud. 



H. farinacea Verrill (Fig. 228). Tentacles 12 in 2 rows; body 

 25 mm. long extended and 3 mm. in diameter; color whitish, with 

 longitudinal bands of brown; disc yellow: north of Cape Cod, in 8 to 

 10 fathoms. 



2. Bicidium Agassiz. Twelve tentacles in a single row; mouth with 

 a proboscis (conchula) : several species. 



B. parasiticum Ag. (Fig. 229). Body 30 mm. long extended and 

 6 mm. thick : parasitic on Cyanea, fixing itself by the mouth on the manu- 

 brium, subumbrella, or in the gastrovascular cavity; also in the sand: 

 Cape Cod to Bay of Fundy. 



3. Eloactis Andres. Body slender and very contractile; tentacles 

 short and ])lunt or capitate and in two rows: 5 species. 



E. producta And. (Fig. 230). Tentacles 20; body with 20 longitu- 

 dinal ridges, 25 cm. long extended; diameter 18 mm.; color whitish or 

 salmon : South Carolina to Cape Cod, buried in the sand or on the under 

 side of stones in shallow water. 



