Antillean Region: Puerto Rican District. 687 
reum. Elsewhere among the mangroves are found Avscennia nitida, Lagun- 
cularıa racemosa, Anona palustris, Conocarpus erectus and occasionally Bucida 
buceras. 
Among the herbaceous plants at the edge of the lagoons may be mentioned Heliotropium 
curassavicum, Batis maritima, Portulaca pilosa, Herpestis Monniera, Chenopodium ambrosioides, 
Pectis humifusa and Capraria biflora. 
In the shallow water among the roots of the mangroves, the phytogeographically inclined 
botanist finds Caulerpa verticillata, Bryopsis plumosa, Codium tomentosum, Catenella opuntia and 
species of the genera Bostrychium and Acanthophora, together with Penicillus capitatus, Udotea 
flabellata, Halimeda tuna, H. tridentata, Caulerpa plumaris, C. crassifolia var. mexicana, C. cupres- 
soides 
The Sandy Alkaline Plain Formation vegetation of this formation is encountered in 
the neighborhood of the salt ponds, where the sandy soil frequently shows an incrustation of salt. 
Again such plains are separated from the sea by a barrier of beach sand. Where the land be- 
comes firm are found Laguncularia racemosa, Avicennia nitida, Conocarpus erectus together with 
Fimbristylis ferrugineus, Pluchea odorata and Wedelia buphthalmoides. The herbaceous plants, 
wever, which characterize the bare stretches of salt and sand are Batis maritima, Salicornia 
ambigua, Sesuvium portulacastrum, Atriplex cristata, Philoxerus vermiculatus, Stenotaphrum ameri- 
canum, Herpestis Monniera, Cyperus viscosus, 
Chaparral Formation. This is found on small islands and in the southern 
parts of St. Croix and the Virgin group. Such a coppice has a grayish par- 
ched aspect owing to the hoary or spiny covering .of many of the plants and 
occupies about one-third part of the surface of the group. 
Here are found in dense association Bromelia pinguin, Cereus floccosus, Opuntia tuna, Leucaena 
glauca, Randia aculeata, Pithecolobium unguis-cat. Among the larger trees of such thickets 
may be mentioned Crescentia cujete, Pisonia subcordata together with those hardly less inferior 
in size, viz.: Comocladia ilicifolia, Elaeodendron m! Bucida buceras, Tecoma leucoxylon. 
The RT of the vegetation varies; for example, the nist finds species of Croton (C. flavens, 
C. astroites) two or three meters tall, associated with ne involucrata, L. camara, Corchorus 
hirsutus and Melochia tomentosa of a less height. The crown of several trees shape ERPEREE 
in growth like an umbrella. Such are Randia aculeata, Citharexylum einereum, Antheryliu 
Lianes are well represented in the chaparral by Bignonia unguis-cati, Metastelma albiflo 
Ipomoea arenaria, Serjania lucida, Cissus trifoliata, Tragia volubilis, Echites suberecta, and Tourne- 
fortia volubilis. The epiphytes all belong to the genus Tillandsia including such species as Ts 
utriculata and T. recurvata. The parasites are Loranthus emarginatus and a Phoradendron. 
ardly to be separated from the Chaparral Formation and yet suffieiently distinet to merit 
attention is a formation first named by Baron EcGErs, the Croton Formation. This forma- 
tion consists of plants which in various ways have become adapted to resist the effects of a dry 
climate, and to exist on a barren rocky soil always found where the moisture is not sufficient to 
decompose the natural surface of the rock. Thus, some of these plants, as of the genus Croton, 
have leaves, which, like the stem, are covered with scales and hairs, containing besides aromatic 
oils which tend to reduce transpiration. Here in the island of St. Croix where this sort of vege- 
tation is typically developed we find Sideroxylon, Bursera, Randia, Acacia, waee: together 
with Croton, Melochia, Corchorus, Wedelia, Waltheria, Solanum aculeatissim S. igne 
S. Dilamense: Cordia, Hibiscus, ua trum. Other neh of this formation are Eh TE 
campechianum, Parkinsonia aculeata, Clerodendron aculeatum, Anthacanthus spinosus, Castela erecta 
and Argithamnia fascieulata. The lianes of this coppice are Metastelma albiflorum and Gonolobus 
maritimus. The succulent plants which are markedly xerophytic and which may be considered 
as constituents of the croton vegetation are Bromelia pinguin, Melocactus communis, Opuntia tuna, 
