Manchester Memoirs, Vol. Ixii. (191 7), No. 4 



IV. "On the Dorsal Mesenteric Filaments in the 

 Siphonozooids of Pennatulacea." 



By Constance M. Lightbown, M.Sc. 



(Communicated by Professor S. J. Hickson, Af.A., £>.Sc, F.J?.S.) 



(Received and read November 13th, igij.) 



Nature of Investigation. 



In the literature of the order Pennatulacea little attention has 

 been paid to the matter of the occurrence of the two 

 dorsal mesenteric filaments in the siphonozooids. The first and 

 most exhaustive examination of their distribution was made by 

 Kolliker in 1872. In 1884 E.B. Wilson examining- mesenteric 

 filaments in the Alcyonaria generally, while adding nothing to our 

 knowledge of their occurrence in this order, summarised Kolliker'f 

 research by the following list : — 



A. Zooids with filaments. 



Pteroeides (Zooids of "Zooidplatte") 



Pennatula 



(Ptilosarcus = ) Leioptilum * 



(Halisceptrum == ) Virgularia 



Pavonaria 



(Halipteris = ) Pavonaria 



Funiculina 



kophobelemnon 



(policella = ) veretillum 



(Stylobelemnon = ) Cavernularia 



* The generic names used by Hickson are added at the right hand 

 side. 



B. Zooids without filaments. 



Pteroeides (Ventral Zooids, Zooids of the 

 " Kiel " and of the upper face of the 

 leaves) 

 Leioptilum 

 Sarcophyllum 

 Virgularia 

 Acanthoptilum 

 Renilla (Wilson 1884, page 18) 



