of Edinburgh, Session 1879-80. 719 
simply the result of the gemmation, and taken alone is not a 
characteristic of any importance.* 
The power of reproducing by gemmation is of more value, and 
seems at first sight to form a distinction between the CLAVELiNiDiE 
and the other Simple Ascidians; this, however, is more apparent than 
real. The buds on the stolons of the Clavelinid^ are developed 
from the ends of the blood-vessels, and are at first merely slight 
enlargements similar to and comparable with the knobs on the end 
twigs of the vessels in the test of an Asddia ; these last vessels 
being homologous with those in the stolons of the Clavelina. 
In Asddia the vessels do not project beyond the test, hut in 
Molgula they are prolonged considerably as hair-like simple or 
branched processes,! and in Ciona, at the base of the test, projections 
exactly like the stolons of Clavelina , having the same structure 
and containing similar blood-vessels, frequently grow out over the 
object to which the individual is attached. 
It thus appears that all the apparatus necessary for budding is 
present in the Simple Ascidians as well as in the so-called Social, and 
that in the former it may even go the length of forming stolons, hut 
these have never been seen to develop into new individuals. 
Philippij; in 1843 gave a short account of an Ascidian he had 
found at Naples, and which he called Rhopaloea neajpolitana. This 
form is elongated, somewhat like a Clavelina in shape ; the branchial 
aperture, however, is eight-lobed, and the atrial six-lobed as in Asddia. 
“ Im obern Drittheil etwa, wo die Yerdickung anfangt merk licher 
zu werden, sassen in einem unregelmassigen Kranz zweispaltige und 
dreispaltige Auswiichse, jungen Ascidien nicht unahnlich.” The 
body is divided into thorax and abdomen joined by a narrow neck; 
the heart is placed on the right side of the intestinal loop, and the 
* If the mere fact of the union of individuals, irrespective of the cause of 
that union, is to he considered an important point, then aggregations of true 
and undoubted Simple Ascidians of the genera Asddia and Cynthia must also 
be considered colonies of Social Ascidians, as they were in the case of Styela 
grossularia by Yan Beneden in 1847 (Mem. de l’Acad. roy. de Belgique, 
t. xx. ). It is now well known that these aggregations are merely caused by 
the proximity and the coalescence of the tests, and indicate no relationship 
whatever between the different individuals. 
+ For an explanation of the true nature of these hair-like processes in the Mol- 
gulidse, see Lacaze-Duthiers, Arch, de Zool. exper. etgen. vol. iii. p. 314 (1874). 
X Muller’s Archiv fiir Anatomie, 1843, p. 45. 
4 R 
VOL. X. 
