636 MUSCULAR TISSUES IN HYDROIDS POLYPES, 



manner the surface is increased. The muscular lamella occupies 

 the sides of these ridges, and so there are many more fibres to the 

 same surface ; the muscle is higher developed and stronger. Such 

 structures have been found in the Med usre (1) belonging to the 

 Hydrornedusa?, in the Syphonophora (2) in the Scyphomedusre (3), 

 and in the Anthozoa Actiniaria (4), and Pennatulidse (5.) 



At first the muscular lamella covers the whole surface of the 

 folded supporting lamella, but with higher development the ridges 

 of the supporting lamella become very nai'row, and the muscles lie 

 only on their sides. The exterior margins of this lamella are 

 continued into processes which are the stalks of the epithelial 

 cells (6.) The centrifugal parts of this lamella may coalesce, and 

 so an apparently Mesodermal muscle is produced. Such structures 

 have been observed in the ring-muscle of the Actinire by Hertwig 

 (7), and in the marginal tentacle of Charybdea by Claus (8.) No 

 complication of the muscular tissue which could be compared to the 



(1) 0. und R. Hertwig. Der Organismus der Medusen. Jena. 187S, Seite 8. 



(2) C. Claus Uber Halistemma tergestinum. Arbeiten aus dem Zoolo- 

 gischen Instistute, Wien, 1878. Seite 7. 



(3) Von Lendenfeld. Uber Cealenteraten der Siidsee, Cyanea Annaakala. 

 Zeitschrift fiir wissenschaftliche Zoologie. Band XXXVII., Seite 511-526. 



E. Haec&el. Monographic der Medusen, Zweiter Theil. Jena., 1881, Seite 

 147. 



(4) I'd// Lendenfeld. Zur Histologic der Actinien. Zoologischer Anzeiger, 

 Land VI., Seite 1S9. 



0. und R, Hi i twig. Die Actinien. Jenaische Zeitscbrift, Band XIII., *eite 

 567, and elsewhere. 



VonHeider. Cerianthus membranaceus Haime. Sitzungsberichte der K. 

 Academie der Wissenschaften in Wien. Band LXXIX, Seite 27, and 

 elsewhere. 



(.3) A. KbUiker. Die Pennatuliden. Abhandl. d. Senkenb. Naturf- 

 Gesellschaft. Band VII , VIII., Frankfurt a. M., 1872. 



(6) Von Lendenfeld. Zur Histologic der Actinien. Zoologischer Anzeiger. 

 Band VI., Seite 189. 



i7) /•'. //' rtwig. Die Actinien der Challenger expedition. Jena., 1S82, 

 Tafel VI. 



(8) C. ('Inns. Ueber Charybdea marsupials. Arbeiten aus dem Zoolo- 

 gischen Institute, Wien, 1878. 



