402 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



In habit much like H. tridens, but readily distinguished by 

 the large peripheral utricles, easily seen with slight magnifica- 

 tion. In dried plants they collapse, the calcareous framework 

 resembling a honeycomb ; the surface of H. tridens seems quite 

 smooth unless considerably magnified. 



Family 2. BRYOPSIDACEAE. 



Vegetative frond unicellular, much branched ; chromatophores 

 numerous small disks, each with one pyrenoid ; the axis pro- 

 ducing below rhizoids, and above branches both of unlimited 

 and limited growth ; in the latter large biciliate, green, female 

 gametes, and on separate individuals, smaller, brown, biciliate 

 male gametes are formed ; by the union of the two a zygote is 

 formed, germinating immediately. Only one genus with us. 



BRYOPSIS Lamouroux, 1809, p. 129. 

 Characters of the family ; marine. 



A genus mostly of warm waters, some few species extending 

 into and throughout the temperate zone ; mostly attractive 

 plants with symmetrical form, glassy membrane and rich color. 

 The forms of our region group themselves around two types : 

 B. plumosa with firm, distichous ramuli, not much smaller than 

 the branch from which they issue ; B. hypnoides with more 

 flaccid ramuli, not distichous, generally more slender than the 

 branch from which they issue. Whether our forms should all 

 be considered as varieties of these two species, or whether we 

 have a number of distinct species, as given below, can be de- 

 termined only by careful study of living plants. 



KEY TO THE SPECIES OF BRYOPSIS. 



i. Ramuli not distichous. 2. 



i. Ramuli distichous, generally unbranched. 4. 



2. Ramuli long, not distinct in character from the branch bearing 



them. i. B. hypnoides. 



2. Ramuli short. 3. 



3. Ramuli forming a dense coating on the stouter, virgate branches. 



2. B. Duchassaingii. 

 3. Ramuli scattered, alternate, or in short, secund series. 



5. B. ramulosa. 

 4. Corticating rhizoidal filaments abundant at the base of the 



branches and ramuli. 4. B. corticulans. 



4. Corticating filaments inconspicuous. 5. 



5. Ramuli in short, subdistant series. 6. B. Leprieurii. 



5. Ramuli mostly in one continuous series. 6. 



