46 
1-11. 
to 
~I 
iyo} 
. The same larva as seen in figure 1. 
. Side view of an embryo which has attached itself to the microscopic slide. 
. View of the base of a specimen in which the caleareous septa are forked at their peripheral ends, the tines 
The mural (epitheeal 2) layer (¢ the.) is already formed, but the septa are not yet 
. An embryo slightly compressed ; 
EMBRYOLOGICAL MONOGRAPHS, 
PLATE XIII. 
Dare niga fone 
and R. y. WILLEMOES-SUUM. 
cap. Capsule. 
cil. Cilia. 
coll, Columella. 
i, Calcareous concretions. 
d. Dorsum ; dorsal mesenteries. 
d.-l. Dorso-lateral mesenteries. 
ec. Ectoderm. 
en. Entoderm. 
en. Thickening of en corresponding to the 
calcareous septa. 
en!!, Inner layer of en. 
ethe. Epitheea. 
git. ol. Oil globules. 
mb. pa. Membrana propria. 
mnt.  Mesentery. 
mur. “Wall” of the calcareous cup. 
msd. Mesoderm. 
nl. Nucleus. 
Actiniaires a polypiers. 
2, 3, 4, 10, 11, 8. 
vit, 
zd. 
zdi. 
Astroides calycularis. Vrom Lacaze-Duthiers, Développement des Coralliaires. 
Arch. de Zool. exp. et gén., Tom. IT. 
Nore. — The sequence of the stages is indicated by the following order of the figures: 1, 6, 9, 5, tse 
. A free-swimming larva with strongly expressed spiral form, which it assumes when in motion. 
indicates the direction of the motion, the aboral end being in advance. 
. Oral aspect of a larva with 12 mesenteries. The twelve lobes thus formed are divided by the first pair of 
mesenteries, as in Actinia (see Plate XI. figs. 12-16), into two groups of 7 and 5 respectively. The order 
of succession of the mesenteries is the same as for Actinia. 
Nore. —It will be seen by comparison that the 5th and Gth are transposed, as compared with 
Actinia ! 
. Oblique view of the aboral end of the same larva. 
. A more advanced larva than the preceding. 
of the forks being short. 
joined to it. 
After having begun, while in the free state, the formation of — 
caleareous nodules in its tissues, it is now attached, and tentacles have made their appearance. 
. The embryo begins to undergo a modification of form. 
tion surrounded by the peristome ; the foot is relatively reduced in size. 
Franules are seen escaping from the mouth, which is placed above. 
The mouth (o7.) is seen at the summit of an cleva- 
before compression the surface showed no trace of a striation, although the 
walls of the body had advanced into the cavity and very young mesenteries were already developed. 
The distinetion between the inner and outer layers is evident. 
Clear space in the region of the gemi- 
native vesicle. 
Germinative spot. 
Mouth. 
Foot. 
Pharynx. : 
protoplasm. 
Primary polypite. 
Rachis. 
Rudimentary zodids. 
Caleareous septa. 
Spiculum. 
Tentacle. 
Short éa; beginning of ta. - 
Testis. 
Ventral. 
Vitellus. 
Zovid. 
Median (or ‘‘ Haupt”) zooid. 
Deuxitme mémoire. 
1878. Pls. XIJ-XV. 
The arrow 
