310 BIOLOGICAL SURVEY OF 



spines, one on each side of the aperture just back of the 

 operculum; often one of these is smaller than the other or 

 may be absent. 



Callopora craticula (Alder), 1857. PI. 6, fig. 4. (Osburn, 

 1912, p. 229 (Memhranipora) , for references and synonymy; 

 1912 a, p. 278 (Memhranipora) , Labrador and Newfoundland; 

 Whiteaves, 1901, p. 96 (Memhranipora), Gulf of St. Law- 

 rence.) One of the commonest species of the region, taken at 

 twelve shore stations and twenty-two dredging stations. It is 

 a very common and widely distributed northern species, and, 

 on the North American coast, ranges from Greenland to south 

 of Cape Cod. 



This beautiful species grows as an incrustation on flat sur- 

 faces, the colonies seldom being over ^-inch in extent. The 

 zooecia are small, usually arranged rather evenly in radiate 

 series. The raised margin of the aperture is provided with 

 about 12 or 14 long spines. The most anterior are longer and 

 stouter than the others. The first pair are directed well for- 

 ward, the second pair more erect, while the remaining ones 

 bend forward and downward over the area in a very charac- 

 teristic manner. The avicularia are comparatively large, lo- 

 cated on the basal part of the zooecium, often wanting. The 

 ooecium is globose, with a raised rib across it near the middle. 

 There are no spines projecting into the pore chambers. 



Callopora lineata (Linnaeus), 1766-1768. (Osburn, 1912, 

 p. 228 (Memhranipora) for synonymy and references; Cor- 

 nish, 1907, p. 76 (Memhranipora) , Canso, Nova Scotia; Whit- 

 eaves, 1901, p. 96 (Memhranipora) , Gulf of St. Lawrence. Not 

 common, but dredged at stations 40, 45, 67, and 69. Like the 

 preceding species, it is common and widely distributed in 

 colder waters. It occurs as far south as the Mediterranean, 

 but on the North American coast has not been noted much 

 south of Cape Cod. 



Growing much as in the preceding species, which it resem- 

 bles, but the colonies reach a larger size and the zooecia are 

 larger. Eight to 12 pairs of spines are present on the margin. 

 These are rather slender and pointed, the anterior 1 or 2 



