5 T. A. STEPHENSON 
Tribe PrycHopactEAE. 1 family. See Ptychodactidae for 
characters. 
Tribe NyNANTHEAR. Sub-tribes included: Athenaria, 
Kndocoelactaria, Mesomyaria, Endomyaria. 
Common characters or tendencies, 7. 
1, Ectodermal muscle in body-wall the exception and not the rule, 
occurring only in sporadicaily-distributed cases. 2. Spirocysts in 
body-wall ectoderm not the rule—only of regular occurrence in 
Endocoelactids. 3. Siphonoglyphes present save in odd _ cases, 
4. Mesenterial filaments with ciliated tracts. 5, Pairs of perfect 
mesenteries present. 6. Mesenterial musculature does not very often 
exhibit so low a grade of development as in the Gonactiniidae, Ptycho- 
dactidae, and many Madreporaria, weakness being usually sporadic 
and secondary rather than universal and inherent. 7. A fundamental 
number for the arrangement of parts is six, but there are a good 
many deviations. 
Sub-tribe ATHENARIA. 2 families. Common characters, 9. 
1. No base (correlated with more or less vermiform shape). 2. No 
basilar muscles. 3. No vesicles. 4. Sphincters weak or absent, 
though if present they may be endodermal or mesogloeal. 5. Not 
more than one tentacle per exo- and endocoel. 6. Tentacles and 
mesenteries few, up to forty or so. 7. Secondary mesenteries exo- 
coelic. 8. Mesenteries divided into macro- and microcnemes, or all 
macrocnemes, with Peachia as an intermediate. 9. No acontia. 
Sub-tribe ENpoconLAcTARIA. 2 families. Common char- 
acters, 9. 
1. Definite base. 2. No genuine basilar muscles. 3. No vesicles. 
4. Spirocysts nearly always in body-wall ectoderm. 5. Probably 
no ectodermal muscle in body-wall. 6. No sphincter. 7. Secondary 
mesenteries endocoelic and oriented as directives. 8. Not more than 
one tentacle per exo- and endocoel. 9. No acontia. 
Sub-tribe Mresomyarta. 10 families. Common characters or 
tendencies, 7. 
1. Definite base with one or two exceptions. 2. Basilar muscles 
usually present. 3, Novesicles. 4. Acontia oR a mesogloeal sphincter, 
or both, present. 5. Not more than one tentacle per endo- and exo- 
coel. 6. Secondary mesenteries exocoelic. 7. No acrorhagi or tenta- 
cular complications of an Endomyarian sort—often there are basal 
mesogloeal swellings to the tentacles, and thick body-walls, however, 
and there are two cases of another sort of tentacular thickening. 
