420 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Occurrence. — 



D. 5141. Jolo Light, Jolo; 6° 09' N.; 120° 58' E.; 29 fathoms; 



co. S. 

 D. 5147. Sulade Island, Sulu Archipelago; 5° 41' 40" N.J 120° 



47' 10" E.; 21 fathoms; co. S. sh. 

 D. 5179. Romblon Light, Romblon; 12° 38' 15" N.; 122° 12' 



30" E.; 37 fathoms; hard S.; 24.2° C. 

 D. 5478. Tacbuc Point, Leyte; 10° 46' 24" N.; 125° 16' 30" 



E.; 57 fathoms; Sh.; 12.4° C. 

 D. 5577. Mount Dromedario, Tawi Tawi; 5° 20' 36" N.; 119° 



58' 51" E.; 240 fathoms; crs. S. 

 Cotypes — Cat. Nos. 8242-8244, U.S.N.M. 



HOLOPORELLA DISCOIDEA Busk, 1884 



Plate 60, figs. 7-9 



1884. Cellepora discoidea Busk, Polyzoa collected by Challenger, Report Scien- 

 tific Results Challenger, vol. 10, p. 197, pi. 30, fig. 8. 



1890. Cellepora discoidea var. frutetosa Kirkpatrick, Hydoida and Polyzoa from 

 Torres Strait, Scientific Proceedings Royal Dublin Society, p. 621, pi. 

 17, fig. 3 (opercula). 



1909. Holoporella discoidea var. frutetosa Waters, Bryozoa, Sudanese Red Sea, 

 Journal Linnean Society London, vol. 31, p. 161 (cited). 



1921. Holoporella discoidea var. frutetosa Marcus, Swedish Scientific Expedition 

 to Australia, Kongl Svenska Vatenskaps-Akademiens Handlingar, vol. 

 61, p. 25, pi. 1, figs. 12-15. 



Measurements . — 



. |k = 0.08mm. n • [Iz = 0.50mm. 



Apertura 7 n , 1 Zooecia 7 OA 



|Za = 0.11 mm. U2 = 0.30 mm. 



Maximum length of avicularium==0.50 mm. 



Structure. — This species is very deceiving and appears like a Schis- 

 mopora. In reality the aperture is hidden at the bottom of the peri- 

 stomie; it is semielliptical like the operculum; the peristomice 

 almost always bears a proximal notch with an avicularian oral umbo 

 on one side. This character is little visible on the variety frutetosa. 



The marginal zooecia are much buried and oriented, while the 

 central zooecia are erect with a central aperture. Close examination 

 of the inferior face of the colony shows on our irregular fragments 

 that the zooecia are arranged in radial rows and that the complete 

 zoarium is really discoidal. 



The ovicells are large, salient, transverse, opened by a large orifice 

 not closed by the operculum. 



The zoarial avicularia are large with a pivot; the beak is spatulate 

 and the mandibular cavity is concave, smooth, rather deep. They 

 are much smaller in the variety Jrutetosa. 



Affinities. — Our fragments were dead; but they appear really to 

 belong to Busk's species. It is very probable that the variety frute- 



