138 PEOCEEDINGS OF THE ISTATIOIirAL MUSEUM VOL.72 



Occurrence. — Albatross Station D. 2320, north of Cuba; 23° 10' 

 39'' N.; 82° 18' 48" W.; 130 fms.; fine coral. 

 Albatross Station D. 2324, north of Cuba; 23° 10' 25" 



N.; 82° 20' 24" W.; 33 fms.; coral. 

 Albatross Station D. 2639, Straits of Florida; 25° 04' 



50" N.; 80° 15' 10" W.; 56 fms.; coral sand. 

 Albatross Station D. 2319, north of Cuba; 23° 10' 

 37" N.; 82° 20' 06" W.; 143 fms.; gray coral. 

 Cotyjpes—C2Li. Nos. 7534, 7535, U.S.N.M. 



Family CELLEPORIDAE Busk, 1852 



Genus HIPPOPORIDRA Canu and Bassler, 1927 



The ovicell is hyperstomial and bears a frontal area. The zooecia 

 are accumulated; the frontal is surrounded by areolar pores and 

 often bears small avicularia. The aperture is formed of an anter 

 and a poster separated by two cardelles. The large interzooecial 

 avicularia are acuminated. 



Genotype. — Hippoporidra (Cellepora) edaxBusk, 1859. 



Range. — Miocene — Recent. 



The known species of this genus are as follows: 



Hippoporidra {Cellepora) edax Busk, 1859, recent, fossil. 



Hippoporidra {Lepralia) calcarea Smitt, 1873, recent, fossil. 



Hippoporidra (Lepralia) maculata Ulrich and Bassler, 1904, Miocene. 



Hippoporidra (Lepralia) parvula Canu and Bassler, 1923, Miocene. 



This is a very natural and homogeneous genus. The zooecia are 

 very small, and their study especially in the fossils, is troublesome and 

 difficult. It is very difficult to differentiate the species. 



Two good figures of the genotype have been published, that of 

 Hincks, 1880, a recent specimen, and that of Busk, 1859, representing 

 a specimen from the English Crag (Pliocene). Both are incomplete 

 but as zoologists we will consider especially that of Hincks. Hippo- 

 poridra calcarea Smitt, 1872, difi^ers in the absence of small frontal 

 avicularia and in a somewhat larger apertural width. Hippoporidra 

 maculata Ulrich and Bassler, 1904, differs from H. edax in its large avic- 

 ularium much less acuminate, in a somewhat larger apertural width, 

 and in the presence of two areolar pores between the frontal costules. 

 Finally Hippoporidra parvula Canu and Bassler, 1923, differs in its 

 transverse aperture and in the presence of three or four small frontal 

 avicularia. 



All these species present curious phenomena of symbiosis. 



The section which we gave in 1923 of Hippoporidra maculata 

 proves that the genus belongs to the Celleporidae and not to the 

 EscharelHdae. 



