454 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Genus HUXLEYA Dyster, 1858 



The aperture is semicircular with a straight poster. No spines 

 no avicularium, no boundary line; 10 tentacles. 

 Genotype. — Huxleya fragilis Dyster, 1858. Recent. 

 The ovicell is unknown. The type has never been rediscovered. 



Fig. 186. — Genus Catenaria D'Orbigny, 1850 



A-F. Catenaria lafontii Audouin, 1826. A. The articulated colony, natural 

 size. Each segment is formed of a simple zooecium. B. Side view, showing 

 the compensatrix, the ovicell and the muscular system (after Harmer, 1902); 

 avic, avicularium, strong, suboral, at the entrance of the compensatrix; cs, com- 

 pensation sac; j, chitinous joint; occl, occlusor muscles of operculum; op, 

 operculum; ov, ovicell placed obliquely on distal side of orifice; pin, parietal 

 muscles; rm, retractor muscles of polypide; sp, circle of short hollow spines 

 surrounding oral extremity of zooecium; z 1 , a pair of new zooecia originating 

 from the back of the distal end. According to Waters, 1907, the ovicell is a 

 thrown-back open one and not closed by the operculum. C. Anterior side of a 

 zooecium showing the distal spines and the concave poster. D. Zooecium 

 viewed from the left side showing the proximal avicularium and the articulation 

 of the distal zooecium. E. Zooecium from the right side. F. Posterior side 

 exhibiting the mode of branching. (A, C-F. After Busk, 1854.) 



Family SCLERODOMIDAE Levinsen, 1909 



The zooecia are formed by a very thick tremocyst with tubules; 

 the very small distal wall is adorned with uniporous septules; the 

 lateral walls have bi-triporous septules. The apertura is buried at 

 the bottom of a Ion?; peristomie. The avicularia are placed in the 



