424 



the Clavelinidae s. str. . Hitherto no true Distornici * has been known 



to possess free zooids — that is zooids not completely embedded in a 



common test; this new Ascidian, however, combines the structural 



characters of the Distomidae with a social form of colony which is 



only slightly removed from that of the Clavelinidae. 



Further, Archidistoma aggregatimi is of especial interest because 



it exhibits the first stage in 

 Fig. 2. ° 



the evolution of the coenobi- 



tic type of colony from the 



,r " Social Ascidian type, in which 



the zooids are entirely free 



and irregularly placed; in 



Archidistoma aggregatimi the 



clumps of zooids ^primitive 



coenobia) have no common 



cloaca, but the cloacas of the 



individuals are usually situated 



towards the centres of the 



groups. The second stage is 



exhibited in such a Compound 



Ascidian as Synoicum turgens 



or Circiiialium concrescens in 



which each of the isolated 



clumps of zooids possesses a common central cloaca. 



Marine Biological Laboratory, Plymouth, July 31st. 1891. 



Fig. 2. Archidistoma aggregatimi. 



Part of another colony, enlarged; shewing 



the partial freedom of the zooids of a clump, 



and the tendency of the cloacal apertures 



towards a central position. 



6. Die Beziehungen von Goniopelte gracilis CIs. = Clytemnestra Hendorffi 



Poppe zu Goniopsyllus rostratus Brady = Sapphir rostratus L. Car, sowie 



deren Stellung im System. 



Von C. Claus, Wien. 



eingeg. 12. September 1891. 



Kurze Zeit nach Publication meiner Schrift über Goniopelte gra- 

 cilis, eine neue Peltidie (Arbeiten d. zoolog. Instituts. Wien. 9. Bd. 

 2. Hft.) erhielt ich Poppe's Beitrag zur Kenntnis der Gattung Cly- 

 temnestra Dana durch die Güte des Verfassers übersandt. Die nahe 

 Verwandtschaft der in dieser Schrift näher beschriebenen und an guten 

 Abbildungen erläuterten ostindischen Clytemnestra Hendorffi Poppe 

 mit der mediterranen Goniopelte gracilis leuchtete aus beiden Be- 



1 The position of Chondrostachys is uncertain, but its nearest affinity seems 

 to be with Stereoclavella rather than with Oxycorynia. Diazona is separated from 

 the Distomidae by the presence of internal longitudinal bars in its branchial sac. 



