Two new coralline algae from Culebra, Porto Rico 



M. Foslie and M. A. Howe 



(with plates 23-26) 



Since the publication of our paper on u New American Coral- 

 line Algae/' * the island of Culebra, lying between Porto Rico 

 proper and St. Thomas and now occupied by the United States as 

 a naval station, has been visited by a collecting party from the 

 New York Botanical Garden. Several coralline algae were secured 

 there, including two rather large and conspicuous kinds which are 

 quite different from any hitherto reported from the West Indian 

 region and are, we think, entitled to characterization as new species. 

 Descriptions of these two species are herewith given : 



Goniolithon acropetum Fosl. & Howe, sp. nov. 



Attached by a rather inconspicuous hypothallus and forming 

 cespitose or difform masses mostly 4-12 cm. high, the single 

 clusters usually 6-15 cm. in diameter, but often confluent and 

 apparently larger; branches repeatedly subdichotomous, much 

 anastomosed, compressed or subterete, 1.25-3.10 mm. in diam- 

 eter, and subtruncate-capitate, or very often much dilated either 

 at apex only or throughout and then forming flabella or foliar 

 laminae 10-25 mm - broad (including anastomoses) and 1-2 mm. 

 thick or commonly thicker in basal parts, the dilated portions 

 often anastomosing in such a way as to form somewhat tubular or 

 subinfundibuliform communicating interstices, the terminal flabella 

 sometimes crested with short subterete or dentiform innovations ; 

 younger branches all conspicuously decutescent, the exfoliations 

 papyraceous, revolute, and more or less concentric or zonate : 

 medullary hypothallic cells 14-40// X 11-20/i; perithallic cells 

 11-21 fix 9-14//, heterocysts numerous; conceptacles of spo- 

 rangia subcorneal becoming mammilliform, about 1 mm. in diam- 

 eter ; sporangia 4-parted, 90-168 /i x 40-102 fi. (Figure i and 

 plates 23, 24.) 



Growing on corals and on other Melobesieae in about 1-4 dm. 

 of water (low tide) in a reef-sheltered cove near the mouth of the 



* Bull. N. Y. Botanical Garden 4 : 128-136. //. 80-gj. 17 Mr 1906. 



577 



