60 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 7B 



the mesopores. There is, then, a kind of exterior calcification rather 

 difficult to understand on incomplete specimens. 



Occurrence. — Galapagos Islands, D. 2813 and D. 2815. 



Holotijpe.—C^t. No. 8533 U.S.N.M. 



HETEROPORA, species 



Plate 9, Figures 4-6 



Our photograph shows two small incomplete colonies. The peri- 

 stome is hardly salient and measures 0.10 mm. in diameter; it bears 

 a small distal visor (galea) directed toward the base of the colony, as 

 in certain Lichenoporas ; its orifice measures 0.08 mm. in diameter. 

 The peristomes are arranged in quincunx distant from each other 

 0.30 mm. and separated by smaller irregular polygonal pores. 



The colony is bordered inferiorily by a smooth basal lamella little 

 enlarged, which appears to be the true zoarial margin. 



Without ovicell or sections it was impossible for us to give an exact 

 idea of the structure of this species. It recalls certain Multicrescis of 

 the Cretaceous, and it would be interesting to make a detailed study 

 of it. 



Occurence. — Galapagos Islands, D. 2813. 



Cat. No. 8534, U.S.N.M. 



