574 T. A. STEPHENSON 
termed the capitulum; it may or may not be very distinct 
from the scapus ; usually it has no cuticle ; it may be delicate 
and different in structure from the scapus, and introvertible 
into the latter. The aboral end of the body if rounded and 
able to become bladder-like is called a physa. Some adherent 
forms possess scapus and capitulum, but ordinary base instead 
of physa ; among these the capitulum may be delicate or may 
be very thick-walled. There are grades between a physa and 
a well-marked adherent base, and some bases may temporarily 
become physa-like. 
CiurarepD Tracts (Flimmerstreifen) of mesenterial 
filaments. In the filaments of Zoanthinaria, Edwardsiaria, 
and Nynantheae, a transverse section cut at the right level 
will show a trifoliate outline, portions of the lateral lobes of 
the trefoil being composed of plain ciliated cells, these portions 
forming, therefore, in the whole filament, lateral ciliated 
tracts on either side of a median glandular or cnido- 
glandular tract (Nesseldrisenstreif). 
Crincur1pEs.—Pores in an Actinian body-wall. Function 
perhaps connected with water-currents ; in some cases they 
seem to provide safety-valves against rupture of the wall on 
sudden jerky contraction. Connexion with acontia secondary 
and indirect. 
Concuuta.—tThe specialized upper extremity of the 
siphonoglyphe in the genus Peachia. Perhaps connected 
with the entry or exit of a water-current when the animal 
is embedded in sand up to the dise. 
CouPpueE of mesenteries. See foot-note. 
Tnpocoen. The space between two mesenteries of the 
same pair.? 
1 In this paper the word ‘ pair’ is used of two mesenteries, both on the 
same side of the body, and adjacent to one another—and usually with 
their retractor muscles vis-&-vis. The word ‘couple’ is applied to 
two mesenteries arising at the same time and symmetrical about the 
long axis of the actinopharynx, but one on one side of the latter, and one 
on the other; their retractors facing the same way. ‘Thus ordinary 
directive mesenteries are strictly couples, though usually called 
pairs for convenience. 
