104 PEOCEEDIlSrGS OP THE NATIONAL MUSEUM vol.72 



GEMELLIPORIDRA MULTILAMELLOSA Canu and Bassler, 1923 



1923. Cyclicopora muUilamellosa Canu and Bassler, North American Later 

 Tertiary and Quaternary Bryozoa. Bull. 125, U. S. National Mu- 

 • seum; p. 138, pi. 46, figs. 3-6. 



This interesting fossil species is somewhat smaller than Gemellipo- 

 ridra typica and differs still more in its small and transverse aper- 

 tm'e and in its much longer avicularia, with the beak always oriented 

 toward the base of the zooecium. 



We were unable to establish the true structure of this species on 

 the fossil specimens previously studied, but the discovery of three 

 recent species now permits us to incorporate it in the genus Gemelli- 

 poridra. 



Occurrence.— ^'Pleistocene: Mount Hope, Panama Canal Zone. 



Pliocene : Minnitimmi Creek, Bocas Island, Almirante 

 Bay, Panama. 



Subfamily Hippoporae Canu and Bassler, 1917 

 Genus HIPPOPORINA Neviani, 1895 



HIPPOPORINA CLEIDOSTOMA Smitt, 1873 



Plate 9, Figure 7; Plate 32, Figure 5; text Figure 18 



1873. Lepralia cleidostoma Smitt, Floridan Bryozoa. Kongl. Svenska Veten- 

 skaps-Akademiens Handlinger, vol. 11, p. 62, pi. 11, figs. 217-219. 

 Not Waters, 1899, Norman, 1909. 



nr J A i f^a = 0.14 mm. 



Measurements. — Aperture-^ 7 



[ta = 0.10 mm. 



„ . fi3 = 0.40-0.50 mm. 



Zooeciaj^^^Q 24-0.30 mm. 



Affinities, — This species is not at all Hippoporina porcellana, Busk, 



1860, found at Madeira and studied successfully by Waters, 1899, 



Fig. 18.— HIPPOPORINA cleidostoma Smitt, 1873. A-E. Diffeeent foems of the 



OPERCULUM which IS MUCH CHITINIZED 



and Norman, 1909. It differs from it in its more elongated zooecia, 

 in its larger and more elongated operculum, and in its aperture much 

 less removed from the distal border of the cell. This error of syn- 

 onymy obhges us to revise our text Figure 114 of 1920. 



The zooecia are very small in the vicinity of the ancestrula and 

 increase regularly up to the border of the colony. The aperture is 



