316 DE. J. E. DUERDEN ON THE 



1898. Haddon, a. C. — "The Actiniaria of Torres Straits." Trans. R. Dublin Soc. vol. vi., ser. 2. 



1898. KwiETNiEwsKi, C. R. — " Actiniaria von Ambon und Thursday Island." Semon, Zool. Forscli- 



ungsreisen in Australicn, &c., Jena. 



1889. McMuRRicH, J. P.— "The Actiniaria of the Bahama Islands, W. I " Journ. Morph. vol. iii. 



1890. Id. — " Contributions on the Morphology of the Actinozoa. I. The Structure of Cerianthus 



americanus." Journ. Morph. vol. iv., no. 2. 

 1893. Id. — " Report on the Actinire collected by the U.S. Fish Commission Steamer ' Albatross •" during 

 the winter of 1887-1888." Proc. U.S. Nat. Mus. vol. xvi. 



1899. Id. — " Contributions on the Morphology of the Actinozoa. V. The Mesenterial Filaments in 



Zoanthus sociatus (Ellis)." Zool. Bull. vol. ii., no. 6. 

 1899. Parker, G. H.—" Longitudinal Fission \u Metridium /Har^rma^MOT, Milne-Edwards." Bull. Mus. 

 Comp. Zool. Harvard, vol. xxxv., no. 3. 



1899. Verrill, A. E. — " Descriptions of imperfectly-known and new Actinians, with Critical Notes on 



other Species. III." Amer. Journ. Sci. vol. vii. 



1900. Id. — ■" Additions to the Authozoa and Hydrozoa of the Bermudas." Trans. Conn. Acad. 



Sci. vol. X. 

 1888. Wilson, H. V. — "On the Development of Manicina areo/ata." Journ. Morph. vol. ii. 



EXPLANATION OF PLATES 25 & 26. 



Reference letters. 



I., II., III., = orders of mesenteries. c.s. = ciliated baud. col.w. = column-wall. d. = directive 

 mesenteries. disc = d\sc. ec/. = ectoderm. ec<.?«. = ectodermal muscle. end. ^endodcvm.. 

 ewrf.wi. = endodermal muscle. ev. = columnar evagination. ^.a". = glandular streak. l.s.=- 

 intermediate streak. »!es. = m°soglcea. mes<.= mesentery. ?n.^/. = mesenterial filament, 

 wew. = nematocyst. w7"./. = nerve-layer. or.sph. :^ora.l sphincter. re<.»«.= retractor muscle. 

 s^.=stomodfeum. /.c.s.=:tentaculo-coelomic septum, t., <eH^ = tentacle. ^.s;;/j. = tentacular 

 sphincter. <>Yms.wi. = transverse muscle. »ooa-. = Zooxanthellae. 



Fig. 1, a, b, c. Three different polyps, somewhat enlarged : a and b in the living expanded condition ; 

 c, a preserved polyp. 



2. Vertical section through a portion of the basal disc, including a tangential section of a mesentery. 



No basilar muscle occurs at the insertion of the mesentery on the basal wall, x 400. 



3. Vertical section through the upper region of a polyp, including a part of one side of a tentacle, 



the upper part of the column-wall, and one side of the tentaculo-coelomic partition with the 

 tentacular sphincter at its free extremity. The poly pal wall in all its three layers is here more 

 swollen than usual, x 400. 



4. Median vertical section through an entire polyp, but including only the basal part of two 



tentacles. The stomodseum is slightly protruding, and several mesenteries are cut obliquely. 

 X 70. 



5. Vertical section through a columnar evagination. x 400. 



