PLATE 21. 



Fig. 54. — Alyriosonm crustaceum Smitt. A few zooecia showing typical 

 orifice (or.), lateral aviciilaria (av.), and ocecia (oe.). X 30. 



Fig. 55. — Myriozo'um coarctaimn Sars. A few immersed zooecia. X 30. 



Fig. 56. — M. coarctatum. Cross section of the stem showing arrange- 

 ment of zooecia around the center. 



Fig. 57. — M. coarctatum. Habit sketch. Natural size. 



Fig. 58. — Myriozoum suhgracile d'Orbigny. A few immersed zooecia 

 showing avicularium {av.) above the orifice. X 30. 



Fig. 59. — Hippothoa divaricata Lamouronx. Habit sketch. X 8. 



Fig. 60. — H. divaricata. A few zooecia showing median keel (l:), and 

 small ocecia on diminutive zooecia. X 50. 



Fig. 61. — Lepralia bilabiata Hiucks. A few zooecia at the growing edge 

 of the colony showing the membranous aperture of the immature zooecia 

 (im. soe.). X 30. 



Fig. 62. — L. bilabiaia. A few adult zooecia. X 30. 



Fig. 63. — L. bilabiata. The operculum dissected out. 



Fig. 64. — L. bilabiata. A single zooecium with its ooecium (oe.) X 30. 



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