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VOL. 72 



Structure. — Osburn did not give the chitinous appendages, so we 

 have prepared them. The operculum bears laterally two very thick 

 sclerites a little attenuated in the distal portion. The tentacular 

 sheath is attached by two pairs of very thick muscles. The mandi- 

 bles of the oral avicularia are semielliptical and strongly chitinized 

 in their distal portion. The mandibles of the large interzooecial 

 avicularia are very large, more or less rounded or somewhat acumi- 

 nated. The muscular bundles are attached to them. 



One of our colonies measures more than 20 square centimeters. 

 It is tinted with brown. 



Fig. 32.— Holoporella magnifica Osburn, 1914. A, B. Mandible of the small zooecial avicu- 

 laria, X 85. C. An ordinary avicularian mandible. D. Isolated operculum. X 85. E. 

 Operculum, X 85, with attached tentacular sheath. F. Tentacular sheath attached to- 

 operculum, X 85. Q. Mandible of an interzooecial avicularium with its two pairs of ele- 

 vator AND OCCLUSOR MUSCLES GROUPED IN SUPERPOSED BUNDLES. H. A SMALL AVICULARIUM, X. 



85. I, J. Mandibles of large interzooecial avicularia, X 85 



Occurrence. — Albatross Station D. 2363, east of Yucatan; 22° 07 

 30" N.; 87° 06' 00'' W.; 21 fms.; white rock coraL. 

 Albatross Station D. 2405, Gulf of Mexico; 28° 45' 

 00" N.; 85° 02' 00" W.; 30 fms.; gray sand, broken 

 coral. 

 Tortugas, 16 meters; and Biscayne Key, Florida 

 (Osburn). 

 Plesiotypes. —C&t. No. 75265, U.S.N.M. 



