490 PEOr. ALLMAN ON THE STETJCTUEE AND 



most obvious peculiarities is the possession of an epistome, an 

 organ somewhat resembling the epiglottis of a mammal, wbicb 

 springs from the lophophore or support of the tentacular crown 

 at the anal side of the mouth, whose entrance it defends .nuch in 

 the same way that the epiglottis defends the glottis. "With one 

 exception — that afforded by Fredericella — the lophophore is in 

 the form of a crescent. 



Strtjctuee. 



We owe to Hyatt a very valuable and well-illustrated memoir 

 on the structure of the Phylactolscmatous Polyzoa*. The genera 

 which form the subject of his observations include, with the 

 exception of Lophopus, all those hitherto found in Europef, as 

 well as a new genus Pectinatella, which, so far as we yet know, 

 is confined to the United States. He has studied the histological 

 structure of the endocyst and of the alimentary canal, the dis- 

 tribution of the muscles and of the nervous system ; and on all 

 these points has added much to our previous knowledge of the 

 group. 



Nitsche has also published the results of a series of very careful 

 and valuable researches on Alcyonella fungosa%, which he takes 

 as a representative of the Phylactolsemata. He does not appear 



would appear to justify these claims are its crescentic lophophore and the 

 possession of a shield-like organ extended over the mouth, and havin^ s.ome 

 resemblance to the epistome of a Phylactol^matous polyzoon. ' 



The crescentic lophophore, however, of Bhabdopleura is very different from 

 that of the PhylactolEemata, the tentacles which it carries forming an inter- 

 rupted series instead of a continuous row round the edges of the lophophore. 

 The shield-like organ, moreover, as shown by its development, has a sig 'ifi- 

 cance entirely different from that of a Phylactol^matous epistome. It is in 

 fact an independent zooid (person) intercalated into the life series of the 

 animal. 



The characters of Bhahdo'pleura are altogether so anomalous as to place it 

 in a great primary section of the Polyzoa, at least equal in rank to those of 

 EcTOPROCTA and Endoprocta — a section for which one of its most striking 

 features, the possession of the great supraoral shield, would suggest the name 



of ASPIDOPHORA. 



* Alpheus Hyatt. "Observations on Polyzoa, Suborder Phylactolsemata," 

 Proceedings of the Essex Institute (United States), 1865, vol. iv. 



t Alcyonella is referred to merely as a form of Plumatella. 



X Nitsche. " Beitrage zur Anat. und Entwick. der Phylactoleemen, insbeson- 

 dere von Alcyonella fungosa," Archiv flir Anat., 1868. 



