POLYZOA 197 



much smaller and narrower than those of M. pilosa ; easily distinguished 

 from that species by its manner of spreading and the absence of the one 

 long hair. Common from New Jersey northward. 



M. tennis. Common on pebbles, often covering their whole surface 

 with a lace-like incrustation of very small oblong cells having a three- 

 lobed aperture Found in Long Island Sound and north to Cape Cod. 



GENUS Escharella 



E. variabilis. This species forms calcareous incrustations on shells 

 or pebbles. The layers are thin, but eventually overlap one another, and 

 the incrustation sometimes becomes an inch thick and resembles coral. 

 The color of the living animal is dull red. The species ranges from Cape 

 Cod to South Carolina, and is abundant in Long Island Sound. 



GENUS Mollia 



M. hyalina. Cells subcylindrical, irregular, transparent, smooth, 

 and more or less oblique. The species forms small circular disks on algaa 

 in tide-pools. 



GENUS Cellepora 



C. scabra. It forms branching, coral-like masses on slender red 

 algae. 



C. ramulosa. Branches cylindrical, rough, dividing in a forking 

 manner, spreading, two to three inches high, calcareous; cells urn- 

 shaped, irregularly arranged, apertures contracted, long spine on the 

 outer edge. It is found in deep water attached to shells, and in tide- 

 pools, where it grows chiefly on Sertularia and other hydroids and on 

 slender red algaa. It ranges from Long Island Sound to Greenland. 

 (Plate LI.) 



C. pumicosa. Cells urn- shaped, irregularly crowded together, form- 

 ing a conglomeration of porous, brittle masses, not exceeding an inch in 

 breadth, usually round when small, oblong and knobbed when large ; 

 spine on outer margin of aperture. It incrusts stones and the stems of 

 Fucus. (Plate LI.) 



SUBORDER CTENOSTOMATA 

 GENUS Alcyomdium 



A. ramosum. Twelve to fifteen inches high; much branched; 

 branches smooth, cylindrical, one third of an inch in diameter, usually 

 crooked ; branches in a forking manner ; color rusty-brown. Abundant 

 in shallow water, attached to rocks, from New Jersey to Cape Cod. 



A. hirsututn. A species common on seaweeds, sometimes completely 

 covering them, forming dirty, straw-colored, thick, cartilaginous crusts 

 covered with numerous conical papillae. These are the cells, or zooecia ; 

 they are surrounded with spines. Circular yellow spots occur over the 

 surface, which are clusters of eggs. A good pocket-lens will show the 

 cells, laid in beautiful order, and perhaps the extended tentacles. Found 

 from Long: Island Sound northward. 



