516 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Genus ACTISECOS Canu and Bassler, 1927 



The zooecia are tubular, swollen at their base; the frontal is a 

 tremocyst with very small pores. The ovicell is peristomial and 

 placed on the dorsal. The aperture is ogival and buried at the 

 bottom of a long peristomie. The base of the zooecia is hexagonal. 



Genotype. — Actisecos regularis Canu and Bassler, 1927. Recent. 



Fig. 214. Genus Orthoporidra Canu and Bassler, 1927 



A-I. Orthoporidra compacta Waters, 1904. A. Zoarium, natural size. B. Por- 

 tion of a zoarium, X25. The lower edge of the oral aperture is straight. Above 

 the oral aperture there is a long process bearing an avicularium with a triangular 

 mandible. The zooecia are porcellaneous. 24 tentacles. C. Operculum, X85. 

 It is straight below, and the muscular attachments are quite at the distal end. 

 D. Mandible from small avicularium on the zooecium, X85. E. Rostral man- 

 dible, X 85. F. Mandible of vicarious avicularium. (A-F. After Waters, 1904.) 



G. Section through a zooecium showing tentacles, ovaria and ova, and the 

 wall of the compensatrix, X85. H. Ovarium, X250. I. Wall of the tentacular 

 sheath, X750. The tentacular crown is three or four times thicker and shows the 

 darkly stained longitudinal muscular band, a character which does not appear 

 to exist in the other genera of the family. (G-I. After Waters, 1905.) 



This genus very much resembles Ascosia Jullien, 1881, but differs 

 from it in having 6 cells around the ancestrula, in the absence of oral 

 avicularia and in the peristomial and not recumbent ovicells. Waters 

 was in error in comparing Ascosia with Mamillopora. 



The differences are great for Ascosia belongs to the Pentapogona 

 according to the figure of Jullien while Mamillopora has 6 cells around 

 the ancestrula. Ascosia is ornamented with long peristomies. The 

 recumbent ovicell is borne on the peristomie in Ascosia and by the 

 zooecium in Mamillopora. 



