REPOET ON THE TUNIC ATA. 
341 
that gemmation takes place in connection with the vascular prolongations from the bodies 
of the Ascidiozooids into the test. A well-marked vessel, enclosed in a prolongation 
of the mantle, leaves the posterior end of each Ascidiozooid (PL XLV. figs. 9, 12) 
. and runs for a longer or shorter distance through the test before ending in a dilated 
bulb (PI. XLV. fig. 9, t.k.). Usually the vessels branch considerably (PI. XLV. fig. 4, v.). 
Figure 9 shows an unusually simple conditionj 
Figure 10 on Plate XLV. represents a transverse section through the terminal 
bulb of a vessel with its covering of mantle, and figure 1 1 shows a pai-t of a similar 
section more highly magnified, exhibiting spaces in the connective tissue of the mantle 
under the columnar layer of ectoderm cells. The three layers seen in this section 
(PL XLV. fig. 11, ec., mes., and end.) are probably continuous with the ectoderm, the 
mesoderm, and the endoderm respectively of the body of the parent Ascidiozooid. 
Bearing in mind the part which similar vascular appendages play in the process of 
gemmation in other Compound Ascidians, the probability is that here also the young 
Ascidiozooids are developed in connection with these enlarged terminal bulbs on the 
vessels. Cunningham speaks of Goodsiria as a “ Social Ascidian,” thereby expressing, 
I suppose, his belief that gemmation takes place by means of vascular stolons as in the 
case of the Clavelinidm. 
Synstyela, Giard. 
Synstyela, Giard, Assoc, franc, pour ravancem. d. Sci., t. iii. Lille, 1874. 
Colony thin and incrusting. 
Ascidiozooids large and closely placed, completely imbedded in the common test. 
Body not divided into thorax and abdomen. 
Test relatively small in amount. Matrix sometimes fibrillated; test cells small; 
bladder-cells absent ; vessels present. 
Branchial Sac well developed. Eudimentary folds present. Internal longi- 
tudinal bars well marked. 
Dorsal Lamina in the form of a plain membrane. 
Tentacles well developed. 
Alimentary Canal not prolonged behind the branchial sac. Stomach folded 
longitudinally. 
Reproductive Organs in the form of polycarps attached to the mantle. 
This genus is one of the two forms very briefly described by Giard in 1874,^ the 
other one being Polystyela. It differs from Polystyela and Tliylacium in having the 
Ascidiozooids depressed and not projecting above the general surface of the colony. 
From Goodsiria and Oculinaria it differs in forming thin incrusting colonies, while the 
Assoc, /rang., Lille, t. iii. 
