RED SEAWEEDS 95 



with numerous forward-pointing branchlets, which in turn have spine- 

 like ramuli of various lengths ; frond flat, broadly spreading ; dark red. 

 It is common at all seasons on the California coast. (Plate XXXVI.) 



GENUS Halosaccion 



H. ramentaceum. Fronds brownish-purple, six to fourteen inches 

 long, coarse and cartilaginous, cylindrical, hollow, compressed, attenu- 

 ated at the base; more or less covered with simple or forked hollow 

 branches half the size of the main stem. In exposed pools the plants are 

 short and densely branched; in sheltered places they are larger and 

 more delicate in texture. They are common on the northern New Eng- 

 land and northern California coasts. (Plate XXXVI.) 



SUBORDER RHIZOPHYLUDKE 

 GENUS Polyides 



P. rotundu*. Frond three to six inches high, cylindrical, cartilagi- 

 nous, repeatedly forked, ends obtuse ; spore-masses form numerous lighter- 

 colored excrescences on the upper divisions of the frond; dark red. 

 Common from New York northward, in deep pools and washed ashore. 

 (Plate XXXVI.) 



SUBORDER SQUAMARIEJE 

 GENUS Peyssonnelia 



P. Dubyi. Frond completely adherent to the rock or stone on which 

 it grows ; color dark purple ; somewhat calcareous ; redder and thicker 

 than next species. It is found at low-water mark or in deep water on 

 the northern New England and northern California coasts. 



GENUS Petrocelis 



P. cruenta. Frond closely adherent, forming dark-purple velvety 

 patches of indefinite outline on rocks and stones. Common north of 

 Cape Cod. 



GENUS Hildenbrandtia 



H. rosen. Forms continuous pink incrustations of considerable ex- 

 tent on stones and rocks at low-water mark. Common everywhere. 



SUBORDER CORALLDTEJE 



The genera of this suborder are characterized by a calcareous 

 or stony incrustation of the fronds, which gives them the appear- 

 ance of corals. Most of the species are tropical. 



