CORALLIXACEAE. 537 



calcified thallus — often so hard and rook-like as to cause them to be over- 

 looked by the uninitiated botanical collector as being simply "calcareous con- 

 cretions" or at least as not belonging to the plant kingdom. For the proper 

 collection of many of the crustaceous forms, one needs to be equipped with a 

 hammer and chisel, a fact that accounts in a measure for the poor representa- 

 tion of this family of plants even in most of the larger herbaria. In tho genera 

 Amphiroa and Corallina, the plant body is erect and regularly jointed; in the 

 other Bermudian genera it is wholly unjointed and may be horizontally ex- 

 panded and crustaceous, or lifted into dome-like or tuberdike elevations, or may 

 be erect, subterete, ramose, and shrub-like. In our forms the reproductive 

 bodies occur in special cavities or conceptacles, appearing usually as dome- 

 shaped or mammilliform superficial elevations visible to the unaided eye. 



Lithothamnium syntrophicum Fosl. forms firmly attached crusts ^-^ of a 

 line thick and an inch or more in diameter on stones-, pebbles, and various 

 calcareous objects at various depths. Its surface is commonly roughened by 

 following closely the inequalities of the substratum and it may in addition 

 develop small irregular nodules of its own. A radio-vertical section shows 

 minute cells in obvious vertical rows, but with little or no suggestion of hori- 

 zontal stratification. The tetrasporangial conceptacles are depressed, hemi- 

 spheric, or somewhat irregular, about i-i of a line in diameter, and as in other 

 members of the genus, their roofs soon show numerous small ostioles, suggest- 

 ing the cover of a pepper-box. The tetrasporangia are zonately 4-divided. 

 The type of the species was from Bermuda, where it was first collected by 

 Farlow. Harrington Sound {Howe). 



Lithothamnium mesomorphum Fosl. forms thin, fragile, partially at- 

 tached, irregularly lobed and proliferous crusts ^-2 inches broad, and i-^ of a 

 line thick, the lobes or proliferations semiorbicular or irregular ami loosely 

 imbricate. Easily distinguished from the foregoing by its partly detache<l, 

 lobed or proliferous, and imbricate habit of growth. Type from Bermuda 

 {Farlow). 



Lithothamnium incertum Fosl. has a crustaceous base that adheres closely 

 to rocks 1-4 ft. below the low-tide line in normally agitated water, but it soon 

 develops erect ramified anastomosing usually flattened branches, often forming 

 compact even-topped, sometimes subhemispheric cushions 1-2 inches high anti 

 3-6 inches broad. The crowded terminal branches are occasionally subterete 

 and |-f of a line in diameter, but are more often decidedly flattened and one 

 line or more broad, and the branching commonly shows a tendency to be con- 

 fined to the plane of flattening. The conceptacles appear externally near the 

 ends of the branches, especially the more flattened ones, as crowded depressed- 

 hemispheric elevations \-\ of a line in diameter. A radio-longitudinal or 

 transverse section after decalcification shows a pseudoparenchymatoua struc- 

 ture, with the thin-walled cells in obvious strata. The general texture is rather 

 delicate and the gases liberated in the process of decalcification commonly tear 

 irregular lacunae in the tissues. Type from Bermuda {Farlow). Red Bay, 

 St. David's Island {Howe). 



