THE GREEN ALGAE OF NORTH AMERICA 401 



ments of central strand fused in pairs at the apex of each seg- 

 ment ; peripheral utricles 20-50/01 diam. Fig. 156. Fla., W. I. 

 Generally distributed in all warm waters ; forming dense tufts, 

 by branching in more than one plane. 



8. H. SCABRA Howe, 1905, p. 241, Pis. XI, XII; P. B-A., 

 No. 1485. Frond up to 25 cm. long, dichotomously, usually 

 much branched, always in one plane ; segments strongly cal- 

 cified, not ribbed, reniform, suborbicular, occasionally deltoid- 

 obovate, up to 14 mm. broad, 1.5 mm. thick; filaments of 

 central strand fused in twos and threes at the joints ; peripheral 

 utricles 27-50 p. diam., each prolonged into an acuminate, often 

 indurated terminal cusp ; in contact for onlj r a small portion 

 of their length, rather easily separated ; sporangia pyriform, 

 160-320 n diam., usually distichously arranged on simple or 

 forked pedicels, covering the margin, rarely the disk of a seg- 

 ment. Fla., W. I. 



This species has passed under the name of //. Tuna, but is 

 amply distinct by the cuspidate peripheral utricles, which are 

 visible under a good lens, and give a rougher feeling to the plant 

 than is found in the smooth-utricled H. Tuna. The material 

 distributed as P. B.-A., No. 167, is partly this species, partly 

 //. discoidea. 



9. H. SIMULANS Howe, 1907, p. 503, PI. XXIX; P. B.-A., 

 No. 1486. Plant up to 15 cm. high, strongly calcified, flabel- 

 late in outline, branching in one plane ; segments discoid, plane 

 or somewhat i-3-nerved, subquadrate to obovate in outline, 

 usually broader than long, margin entire, crenulate, dentate or 

 lobed ; up to 12 mm. wide, to 2 mm. thick ; peripheral utricles 

 33-40 n diam., in contact one-third to one-tenth of their length, 

 rather firmly adhering. Filaments of the central strand coher- 

 ent at the nodes, connecting by open pits or very short tubes. 

 W. I. 



Individuals of this species often resemble H. Tuna or //. tri- 

 dens in some habit characters, but it is seldom that there is 

 doubt on considering all the characters. 



10. H. FAVULOSA Howe, 19053, p. 563, PI. XXIII, fig. 2 ; 

 PI. XXVI, figs. 1-6. Fronds up to 20 cm. high, rather thickly 

 calcified, branching densely in one plane ; segments varying 

 much in form, cylindrical to trilobed or discoid, up to 9 mm. 

 long and broad, and 2 mm. thick. Filaments of central strand 

 connected at the joints by very short processes ; peripheral 

 utricles 110-260 /x across. Bahama. 



