308 Proceedings of Royal Society of Edinburgh. [? 
Protomere. 
Mesomere. 
Proto- 
mere. 
Protocoele. 
Protoccelic 
pore. 
Mesomere 
i Mesocoele. 
Mesocoelic 
pore. 
HemichorcLa, .... 
Proboscis. 
Proboscis 
cavity. 
Proboscis 
pore. 
Collar. 
Collar 
cavities. 
Collar 
pores. 
Diplochorda — 
a. Cephalodiscus, . . 
Buccal 
shield. 
Cavity of 
buccal 
shield. 
Proboscis 
pore. 
Collar or 
tentacular 
segment. 
Collar 
cavities. 
Collar 
pores. 
b. Phoronis, .... 
Epistome. 
Cavity of 
epistome. 
(Opens into 
mesocoele.) 
Lopho- 
phoral 
segment. 
Lopho- 
phoral 
cavity. 
(Opens 
into 
metacoele) 
Chcetognatha , .... 
Head. 
Head 
cavities. 
? 
Trunk. 
Trunk 
cavities. 
Oviducts. 
? 
EcMnodermata, 
Brachiopodci, .... 
Epistome. 
(Ampulla.) 
(Axial 
sinus.) 
(Parietal 
canal.) 
Epistomial 
sinus. 
Madrepo- 
rite. 
(Opens into 
mesocoele.) 
Water- 
vascular 
system (L) 
Lopho- 
phoral 
segment. 
Cavity of 
water- 
vascular 
system. 
Lopho- 
phoral 
cavity. 
Opens 
into 
protocoele. 
(Opens 
into 
metacoele) 
Ectoprocta, .... 
Epistome. 
Epistomial 
sinus. 
(Opens into 
mesocoele.) 
Lopho- 
phoral 
segment. 
Lopho- 
phoral 
cavity. 
(Opens 
into 
metacoele) 
Larval Phoronis, 
Pre-oral 
lobe. 
Cavity of 
pre-oral 
lobe. 
Proboscis 
pores. 
‘ Collar.’ 
Collar 
cavity. 
Nephridia 
(Larval). 
Larval Brachiopoda, . 
‘ Head ’ 
segment. 
Trunk 
segment. 
Larval Echinoderm, . 
Pre-oral 
lobe. 
Anterior 
b. c. 
Water 
pore. 
Water- 
vase. 
system. 
Hydro- 
coeles. 
Open 
into 
protocoele 
Larval Balanoglossus, 
Pre-oral 
lobe. 
Anterior 
b. c. 
Proboscis 
pore. 
Collar. 
Collar 
cavities. 
Collar 
pores. 
Larval Polygordius , . 
Pre-oral 
lobe. 
Cavity of 
p. o. lobe. 
•• 
Post-oral 
region. 
Cavity of 
post-oral 
region. 
Larval 
nephridia 
Amphioxus, .... 
Pre-oral 
lobe. 
Pre-oral 
head 
cavities. 
Pre-oral 
pit. 
Post-oral 
region and 
metapleu- 
ral folds. 
Cavity of 
1st myo- 
tome and 
meta- 
pleural 
cavities. 
? 
Annelida, . . . . 
Prosto- 
mium. 
Prostomial 
cavity. 
Peristo- 
mium. 
Cavity of 
peristo- 
mium. 
? 
Vertebrata, .... 
.. 
Pre-man- 
dib. head 
cavities. 
... 
.. 
Mandib- 
ular head 
cavities. 
... 
