AST. 14 FOSSIL AND EECENT BEYOZOA — CAKTJ AND BASSLEB 107 



1906. Eschara nordlandica Nordqaakd, Bryozoa from the second From 

 Expedition, 1898-1902. Report second Norwegian Expedition 

 Fram, p. 22. 



1912. Lepralia pertusa Osburn, Bryozoa of the Woods Hole Region. Bull. 

 Bureau of Fisheries, vol. 30, p. 241, pi. 26, fig. 56. 



1918. Hippoporina pertusa Nordgaard, Bryozoa from the Arctic regions. 



Tromso Museums Aarshefter, vol. 40, p. 59. 



1919. Hipporina pertusa Osburn, Bryozoa of the Crocker Land Expedition. 



Bulletin American Museum Natural History, vol. 16, p. 611. 



,, ^ A . [/ia = 0.14-0. 18 mm. 



Measurements. — Aperture^ , rv , <-■ ^ «r. 



Ua = 0.1 8-0.20 mm. 



„ . fX2 = 0.60-0.70 mm 

 Zooecia{ 



U2 = 0.40-0.50 mm 



Structure. — The frontal is formed by an olocyst surmounted by a 

 tremocyst with small pores; the latter is incomplete in the vicinity 

 of the aperture so that the subjacent olocyst is visible in the proximal 

 portion of the aperture; the peristome limits the tremocyst and not 

 the aperture and it is more or less expanded. 



The ovicell is developed between the olocyst and the pleurocyst of 

 the distal zooecium in which it is embedded. The operculum closes 

 the ovicell; it is semielliptical, transverse. The muscles are attached 

 to a lateral point of an inner peripheral band somewhat thickened on 

 the sides. The operculum does not resemble that which Nordgaard, 

 1905, illustrated for his Eschara nordlandica. The zooecia are little 

 convex and separated by a salient thread. 



Affinities. — The older bibliography of this species is rather confused; 

 for the geographic distribution it is prudent to rely only upon deter- 

 minations made after the publication of the more exact figures of 

 Hincks, 1880. We do not see any great difference from Flustra mang- 

 nevilleana Savigny-Audouin, 1828. According to Smitt, the apertu- 

 ral width of the latter is 0.23 mm. and, according to the pubhshed 

 figures, the zooecia are more convex, not separated by a salient thread, 

 and the cardelles are more salient and placed a little higher. We have 

 been able to compare directly our specimens from Habana with those 

 of Le Cioisic (France). 



Biology. — The species appears to be in reproduction almost all the 

 year. It grows on algae as well as on solid bodies; but it fixes itself 

 very rarely on siliceous pebbles. Its bathymetric range is rather large 

 but it prefers the more shallow waters. It is rarely observed below 

 100 meters; one time on the Newfoundland Banks it was dredged at 

 155 meters of depth. It characterizes the Temperate Zone and does 

 not extend beyond the Tropic of Cancer or the Polar Circle. Its 

 presence in the Pacific is still doubtful. The determination of the 

 fossils must be revised; however, it appears to begin in the European 

 Miocene. 



