326 



BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



Genus HIPPOTHOA (Lamouroux, 1821) Hincks, 1880. 



Zoological bibliography. 1877. BAKROIS, Eecherches sur 1'eiubryologie cles Bryozoaires, Tra- 

 vaux de 1'Institut de zoologie, fasc. 1, p. 149, pi. 0, figs. 4, 16. 1S86. JUIXIEN, Mission scien- 

 tifique du Cap Horn, vol. 6, Zoology, p. 28, pi. 4, figs. 1-4. 1900. WATEES, Bryozoa from Franz 

 Joseph Land. Journal Linnean Society. London, vol. 28, p. 70, pi. 8, figs. 16-18. 1900. LKV- 

 INSEN, Morphological and systematic studies on the Cheilostomatous Bryozoa, p. 276, pi. 18, 

 fig. 9. 1904. WATERS, Expedition Antarctique. beige, Bryozoa, p. 53, pi 3, fig. 8. 



FIG. 93. Genus Hippothoa Lamouroux, 1821 (Hincks, 1880). 



A-I. Hippotlwa hyalina Linnaeus, 1758. A. Portion of zoarium, X 25. B. Zoarium with 

 ovicelled zooecia, X 36. (After Hincks, 1880.) C. Free larva, profile view, X 75. D. Oral 

 face of larva, showing the singular structure of the stomach, X 75. E. Aboral face of larva, 

 X 75, showing the simplicity of the structure of the terminal bud. (G-E after Barrois, 1909.) 

 <:&, digestive cavity ; ce, obscure portion of the body cavity included between the two branches of 

 the stomach (=orifice of the external sack) ; est, stomach; fl, flagellum ; o, mouth of the gas- 

 trula (=ciliated cleft); oc, oculiform points (=pigment spots); ph, pharpnx ; pi, vibratile 

 plume; rv, border of the terminal bud (=calotte). F. Operculum of male zooecium, X 85. G. 

 Operculum of ordinary zooecium, X 85. H. Operculum of ovicelligerous zooecium, X 85. (F-H 

 after Waters, 1900.) I. A sagittal section through a gonozooecium. The ovicell is surrounded by 

 a kenozooecium. (After Levinsen, 1909.) J, K. Hippothoa bougainvillei, D'Orbigny, 1839. 

 J. Young, uniserial zoarium with a spinous ancestrula and with a gonoecium without poly- 

 pide. X 53. f J, K after Jullien, 1S88. ) K. Young zoarium exhibiting spinous ancestrula with 

 opesium, X 53. 



The frontal of the zooecia is not porous. The operculum is compound. The 

 aperture is provided with two much developed hinge-teeth and with a more or less 



