544 T. A. STEPHENSON 
of body. 6. No developed sphincter. 7. Tentacular longitudinal] 
muscle ectodermal. 8. Tentacles not branched, but knobbed. 
9. More than one tentacle on at least each of the strongest endocoels. 
10. Not more than one tentacle per exocoel. 11. No true siphono- 
glyphes.!. 12. No division of mesenteries into macro- and micro- 
cnemes. 13. Usually numerous perfect mesenteries. 14. Feeble 
mesenterial musculature. 15, Filaments with no ciliated tracts. 
16. No acontia. 
DiscosomIpAE. Genera: Discosoma, Paradiscosoma, 
Orinia, Actinotryx, Ricordea, Rhodactis. 
Common characters, 12. 
1. No horny or limy skeleton. 2. Definite base. 3. No basilar 
muscles. 4. No developed sphincter. 5. Tentacular longitudinal 
muscle ectodermal, such as it is. 6. More than one tentacle on at 
least each of the stronger endocoels. 7. No true siphonoglyphes.? 
8. No division of mesenteries into macro- and microcnemes. 
9. Usually numerous perfect mesenteries. 10. Feeble mesenterial 
musculature, not forming true retractors. 11. Filaments without 
ciliated tracts. 12. No acontia. 
N.B.—In this family the tentacles may be reduced or practically 
absent, and their form is variable ; sometimes there is more than one, 
on exocoels as well as endocoels. 
Haucampipar. Genera: Halcampa, Halcampoides, 
Pentactinia, Scytophorus. Common charac- 
ters, 8. 
1. No base (correlated with more or less vermiform shape). 2. No 
basilar muscles. 3. Sphincter absent or weak (if present may be 
mesogloeal or endodermal). 4. Tentacular longitudinal muscle 
ectodermal. 5. Mesenteries divided into macro- and microcnemes, 
or all macrocnemes. 6. Six pairs of macrocnemes the average (may 
be four or five to seven couples). 7. Few mesenteries and tentacles— 
up to forty or so. 8. No acontia. 
InvanTHIpAE. Genera: Ilyanthus (mitchelli), Pea- 
chia, Eloactis, Haloclava, Harenactis. Com- 
mon characters, 8. 
1. No base. 2. No basilar muscles. 3. No developed sphincter. 
4. Tentacular longitudinal muscle ectodermal. 5. Mesenteries all 
1 With regard to this statement, see definition in Part II], covering 
Corallimorphidae and Discosomidae. 
