332 BIOLOGICAL SURVEY OF 



The peculiar shape of the zooecial aperture is the most dis- 

 tinguishing character. It is elongate, rounded anteriorly, and 

 posteriorly suddenly widens until it is much broader than the 

 anterior portion. The proximal border is straight or nearly 

 so. The zooecia are usually arranged quite regularly in a 

 flat crust. The front is thickly punctured with rather large 

 rounded pores. Ovicells and avicularia are wanting. 



HippOPONELLA Canu and Bassler, 1920 

 HippopoNELLA Hippopus (Smitt), 1867. PL 10, fig. 3; pi. 11, 

 figs. 3-4. (Wliiteaves, 1901, p. 101 {Lepralia), Gulf of St. 

 Lawrence; Osburn, 1912a, p. 282 (Lepralia), Labrador.) 

 Abundant one stones from hard bottoms, only once at a shore 

 station 12. The species is a common North Atlantic form, 

 ranging from Spitzbergen and Greenland southward along 

 both coasts to the British Islands and Cape Cod. 



The zoarium is white and glistening. The aperture is round 

 anteriorly, nearly straight on the posterior border, with a 

 pair of large denticles on the sides near the posterior border, 

 giving the aperture somewhat the appearance of a horseshoe. 

 Rounded or short oval avicularia are situated irregularly on 

 the front of the zooecium, often several of them on one zooe- 

 cium. The ooecium is hemispherical, smooth, and imperforate. 

 Secondary calcification is usually very heavy, so that even 

 the ooecium may be completely covered. 



Microporellinae Canu and Bassler, 1917 

 MiCROPORELLA Hincks, 1877 

 MicROPORELLA ciLiATA var. STELLATA (Verrill), 1875. PL 8, 

 figs. 8-9. (Osburn, 1912, p. 233, synonymy and references.) 

 Common, taken at three shore stations and eighteen dredging 

 stations. It is world-wide in distribution and runs into nu- 

 merous varieties, of which the Porellina stellata of Verrill 

 is one common on all the New England coast. It is a heavily 

 encrusted form, in which the secondary calcification largely 

 conceals the primary characters. It has been discussed by 

 Osburn (I.e.). The presence of a stellate pore just proximal 



