750 THE AMERICAN NATURALIST. [VoL XXXIV. 
5. Polyp very slender, length 30 mm., diameter 1.5 mm. ; tentacles six- 
teen ; parasitic on Mnemiopsis leidyi E. leidyi Ver., M.! 
6. Polyp slender, length 125 mm., though canale of contracting to 35 
mm., diameter 4 mm. S tentis twenty to thirty-six ; column with a 
brownish eet PE at aboral end, which is naked 
. sipunculoides (Stimp.) Andres, N., low water (F ig. 1) 
6. Polyp Hae length 25-35 mm., diameter 2.5-3 mm. ; tentacles 
twenty-four to d ; column including aboral end with a brownish 
investment . ^ . E. lineata (Ver.), M., 4-12 fathoms 
Fic. 1.— Edwardsiella sipunculoides (Stimp.) Andres. After Verrill. 
FAMILIES OF HEXACTINLE. 
7. Pedal disk absent- A ; ; } i .  Ilyanthidæ 11 
7. Pedal disk present ; i ; oto ctp o oa. ME 
8. Acontia present NU Pond eheu . o. | Sagari ae 
8. Acontia absent í : : à ; 9 
9. Sphincter diffuse aid kik s : : : > Boloceride 18 
9. Sphincter strong ia 
10. Sphincter endodermal Shei ih titercubdted Bunodide 20 
10. Sphincter mesogleal (column usually not tuberculated) Paractide 31 
GENERA AND SPECIES OF ILYANTHID#. 
11. Conchula (proboscis) Saree ; : : . . Bicidium 12 
r1. Conchula absent : 
12. Polyp elongated, iiem. 30 mm., THREE 6 mm., longitndinal sulca- 
tions twelve ; tentacles twelve ; usually parasitic on Cyanea arctica 
Bicidium parasiticum Ag., N. (Fig 2) 
13. Column divided into three sections, an oral retractile capitulum, an 
intermediate scapus, and a pedal physa : Halcampa 14 
13. Column continuous, not divided into sections . 15 
14. Polyp elongated, length 25 mm., diameter 3 mm. eae twelve 
Halcampa farinacea (Ver.) Andres, N Bas fathoms (Fig. 3) 
14. Polyp slender ; tentacles about twenty-four 
H. pallida (Ver.) Andres, z e water 
15. Tentacles blunt or club-shaped mac eT actis 16 
15. Tentacles tapering to a point . . naia H 
16. Polyp much elongated, length 200-250 mm., whieh may by contraction 
be reduced to 75 mm., diameter 18 mm., longitudinal sulcations 
twenty ; tentacles twenty 
Eloactis Pora (Stimp.) Andres, M., low water (Fig. 4) 
1 Known only as an immature form. 
* 
