THE MOUNT DESERT EEGIOX 321 



four short spines project forward on the anterior border. 

 These may be seen only in the marginal cells of the colony. 

 Avicularia wanting. The ooecinm is small, hemispherical, 

 punctured with a few pores, and with a heavy rib bordering 

 the aperture. Frequently infertile zooecia of smaller size 

 than usual stand nearly erect between the ordinary zooecia. 



Suborder ASCOPHORA Levinsen, 1909 



Hippothoidae Levinsen, 1909 



HipPOTHOA Lamouroux, 1812 



HippoTHOA HYALiNA (Liunaeus), 1766-1768. PL 9, figs. 1-3. 

 (Osburn, 1912, p. 235, for synomTny and references, and 

 1912 a, p. 280, for additional Canadian records ; Whiteaves, 

 1901, p. 100, for Canadian records.) The most abundant bryo- 

 zoan of the region, taken at eighteen shore stations and thirty- 

 five dredging stations. It is one of the most cosmopolitan 

 species known, being circumpolar and circumtropical and 

 ranging from the high arctic to the tropics, and in the south- 

 ern hemisphere to Cape Horn and the Kerguelen Islands. It 

 grows in great profusion all along the New England and 

 eastern Canadian coasts. 



It shows a great amount of superficial variation, though the 

 fundamental characters are fairly constant. Young colonies 

 always present much the same appearance, with rather elon- 

 gate, transversely wrinkled, semihyaline zooecia, well sepa- 

 rated and showing interspaces. As the colonies become ma- 

 ture, the zooecia become heaped up, more or less erected, and 

 turned in every direction. Also in this state large numbers 

 of the dwarf fertile zooecia are produced, and these with their 

 ooecia give an altogether different appearance to the colony. 



Encrusting stones, shells, algae, and stems of various sorts. 

 In the young colony forming rather regular hyaline encrusta- 

 tions, but older colonies become very irregular, the cells piling 

 up on each other, more or less erected, and forming rough 

 crusts. Zooecia are elongate, subcylindrical, narrowed proxi- 

 mally; the surface hyaline, glossy, and transversely rugose. 

 The orifice is rounded, with a broad, well-defined sinus on the 



