644 MR. J. E. DUEEDEIS' ON THE RELATIONS OE 



absence of the riimmerstreifen * is stated by Carlgrea (1893) to 

 be characteristic of the genera Protanthea and Gonactinia, con- 

 stituting the family Gronactinidae ; Appelloff (1893, p. 12) notes 

 their absence in Ptychodactis patidci, the Ne&seldriisenstreifen 

 only being present ; and McMurrich (1893, p. 139) states that 

 the Flimmerstreifen appear to be lacking in the Protactinian 

 Oractis Diomedeoe. Though usually strongly developed in all 

 Zoanthidse, I have lately found the Flimmerstreifen to be 

 absent in a new West-Indian JEpizoanthus. As regards the 

 corals, however, the assertion of "Wilson still expresses the 

 condition in the group. No example, so far as I know, has yet 

 been described with more than a single lobe to the filament, and 

 this holds for the dozen or so species of Antillean corals which I 

 have already sectionized. 



In view of this almost universal presence of trilobed filaments 

 in the middle region of the mesenteries in Actiniaria, and of 

 only the simple form throughout in Madreporaria, it is of some 

 phylogenic significance to find that in no part of the lengtli of 

 the mesentery are lateral lobes observable in the West-Indian 

 species of Corynactis, Picordea, and JRJiodactis. 



Sections through the backwardly directed terminal region of 

 the stomodseum of Corynactis show no difference whatever from 

 sections through the same region in the coral Cladocora. In 

 each the ectoderm of the stomodaeum is in unbroken continuity 

 with the deeply- staining filaments at the free edge of the chief 

 mesenteries. In each the filaments are at first cordate in section, 

 and throughout are sharply marked off" from the rest of the 



* The German terms Driisenstreif or Nesseldriisenstreif and Flimmerstreif, 

 and their English equivalents "glandular streak" and "ciliated streak," are 

 not strictly synonymous with the terms middle and lateral lobes, though usually 

 so regarded. The former refer to parts with a definite histological structure, 

 and I hope to show in a svibsequent paper that only a limited region of 

 the middle lobe of the trilobed filament can be regarded as the morphological 

 Driisenstreif or glandiilar streak, and, similarly, only a portion of the lateral 

 lobes is really the Fhmmerstreif or ciliated streak. 



The free extremity of the mesenteries in nearly all coral polyps displays 

 a more or less trilobed outline in transverse sections, but the two lateral 

 lobes are here only enlargements of the ordinary mesenterial epithelium, 

 are devoid of a mesogloeal axis, and hear no relationship to the lateral lobes of 

 a typical anemone with the ciliated streak. In many of the latter the 

 mesenteries in the proximal parb of the polyp may be similarly trilobed, 

 even though below the region over which the ciliated streak extends. 



