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PACIFIC SCIENCE, Vol. XIX, April 1965 
pharynx and bearing thickened filament upon 
its free inner edge below actinopharynx. 
Mesogloea (Bourne, 1887:30$, 311-320; Tor- 
elli, 1952:154-156) — supporting layer be- 
tween ectoderm and endoderm. 
Metacneme (Duerden, 1900:47, 1902:388- 
397 ) — metamesentery {q.v.). 
Metamesentery (Carlgren, 1912^:50-51, 59; 
1912^:361) — any mesentery other than pro- 
tomesenteries. 
Metasome (Beneden, 1923:21-22) — central 
portion of body excluding prosome and telo- 
mere {q.v.). (by analogy to Amphioxus) . 
Microbasic mastigophore (Weill, 1934:38, 58- 
64, 624-626) — mastigophore in which shaft 
is at most three times capsule length. 
Microbimesenterium ( Carlgren, 1912^:51) — 
microbiseptum {q.v.). 
Microbiseptum ( Beneden, 1 897 : 2 3-24 ) — two 
shorter mesenteries of metamesenterial quar- 
tette. 
Microseptum (Faurot, 1891:68— 69; 1895:233— 
234; Torelli, 1960:374) — one of two short- 
est metamesenteries in quartette. 
Mononeme (Beneden, 1923:79-80) — aboral 
monofilar region of mesenterial filament. 
Mouth (Rapp, 1829:654; Haime, 1854:350, 
372) — opening from exterior to cavity of 
actinopharynx. 
Mucocraspedoneme (Carlgren, 1912^:71) — 
acontioid {q.v.). 
Multipication chamber (Vogt, 1888:24) — in- 
termesenterial chamber opposite directive 
chamber, in which new mesenterial couples 
are formed. 
Mundscheibe (Hertwig and Hertwig, 1879: 
471; Heider, 1879:212)— oral disc {q.v.). 
Nematocyst (Haime, 1854:354-357, 365; Be- 
dot, 1886:51-52; Cuttress, 1955:124-126) 
— capsule containing an expellable coiled 
tube. 
Nematocyst (Bedot, 1889:607-608; 1896:535- 
536; Weill, 1934:330) — -nematocyst sensu 
Haime excluding spirocysts. 
Odd tentacle (Agassiz, 1863:527; Fischer, 
1889:24) — directive tentacle {q.v.). 
Oesophagus (Haacke, 1879:276, 293; Jourdan, 
1879:103, 108-109) — actinopharynx {q.v.). 
Oral disc (Faurot, 1895:47-48, 218) — disc at 
one end of animal bearing mouth and tenta- 
cles. 
Order of mesenteries (Carlgren, 1912 &: 375- 
37 6, 386; Torelli, 1960:374) — all metames- 
enteries of same relative lengths in their 
respective quartettes. 
Orthocraspedon (Bourne, 1919:55-57) — tri- 
neme {q.v.) . 
p. superscript { Beneden, 1923:23) — belonging 
to third somatomere of prosome {q.v.). 
P (Carlgren, 1912:8)— protomesentery {q.v.). 
Peloton (Faurot, 1895:235-236; Beneden, 
1897:27, 46; 1923:51-52, 79)— highly con- 
voluted section of mononeme. 
Penicillus (Stephenson, 1929:178-179; Weill, 
1934:91-92) — nematocyst containing short, 
stout, armed tube (not in present use). 
Peristome (Vogt, 1888:29)— portion of oral 
disc between tentacle crowns. 
Plectocraspedon (Bourne, 1919:55-57) — por- 
tion of mononeme indistinctly delimited by 
abundance of large, thick-walled nemato- 
cysts and large coarsely-granular gland cells, 
usually anterior to telocraspedon. 
p -mastigophore (Carlgren, 1940: 3—4; Cuttress, 
1955:129-131, 133-134; Hand, 1961:189- 
190, 193) — mastigophore in which abrupt 
reduction of shaft to terminal tube allows 
funnel-shaped invagination of axial body. 
Proto cneme (Duerden, 1900:47; McMurrich, 
1910:6-10) — protomesentery {q.v.). 
Protomesentery (Carlgren, 1912^:50-51, 59, 
1912^:361) — one of mesenteries arising in 
first embryological stage (presently consid- 
ered to be one of the first three mesenteries 
on either side of directive plane at siphono- 
gi yph)- 
Prosome (Beneden, 1923:21) — anterior por- 
tion of body including three cycles of proto- 
mesenteries and associated tentacles, inter- 
mesenterial chambers adjoining and portions 
of columnar wall, peristome and actinophar- 
ynx (by analogy to Amphioxus) . 
Quartette of metamesenteries (Faurot, 1891: 
67-68; 1892:238; 1895:231 -234) —any 
group of four mesenteries in a series as 
counted from protomesenteries, each group 
showing similar pattern of relative mesenter- 
ial lengths. 
