8 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. XI. 
ently they are to be sought with confidence on the few islands of any size for which none are yet 
known. As arule, except for the larger islands and the Leeward group of the continental shelf, 
only one form is found on an island, and each is confined to a single island or to islands rising 
from acommon bank. The impression produced is that each main division of the archipelago 
possesses a distinctive species of large-flowered Agave differentiated into minor forms on its 
several islands. The coordination of these forms, however, reveals such manifold agreements 
and differences in characters as to result in the conviction that they themselves constitute 
species, in a conservative sense, and that the more comprehensive and widely distributed 
types are really groups of species rather even than superspecies; and they are so treated here. 
Of the 50 species here recognized for the West Indian flora, 3 (pls. 106—-115)—Agave 
angustifolia, A. fourcroydes, and A. sisalana—are clearly introductions, and represent a group 
of the Yucatan region. The other species are all endemic. Five of them are confined to islands 
on the continental shelf adjacent to the Venezuelan coast, where a closely allied species occurs 
on the mainland; and, though the affinity is not very close, these appear to be related in a 
manner to the as yet uncharacterized Costa Rican Agave Werckler. None of the others shows 
close relationship with any form of the North American table-land, on which, especially in 
Mexico, the genus centers. - ; 
Even on superficial examination, the indigenous species fall into three groups: A small- 
flowered rigid-leaved very xerophytic type (pls. 101-105), confined to the Inaguas; a small- 
flowered fleshy-leaved type (pls. 93-100), of Cuba and its islets; and a medium or large-flowered 
fleshy-leaved type (pls. 1-92), ranging through the entire chain of islands and reaching the 
Venezuelan coast. Closer acquaintance with it shows that this third type—the representatives 
of which are mostly stately plants, rivaling in size the well-known century plant (A. americana) 
with which they have often been confounded—treally consists of four separable groups: (a) An 
ample-panicled capsule-bearing type with usually green leaves ending in a long grooved spine 
and often repand and bordered with rather large prickles (pls. B and 41-82), of the Greater 
Antilles; (b) a similar but rather smaller-panicled type with mostly gray leaves ending in a 
long flat or grooved spine and bordered with moderate prickles (pls. B and 83-92) of the 
Bahamas; (c) a rather narrow-panicled sometimes exclusively bulbiferous type with usually 
green, straight and rosy edged leaves ending in a little-grooved short spine or mucro, below 
which, however, the leaf tip hardens into a heavy involute base, and bordered with minute or 
close-set prickles (pls. B and 14-40), of the Caribbees and Leeward Islands; and (d) a smaller 
if anything more succulent type with green or glaucous rather repand leaves ending in a long 
and usually slender grooved or involute spine and bordered with rather slender prickles (pls. 
B and 1-13), which is peculiar to the Leeward Islands and the adjacent Venezuelan mainland. 
The small-flowered forms comprise two not intimately if at all allied groups: (a) Inaguenses 
(2 species), limited to the Inagua and Caicos islands; and (b) Antillares (5 species and one 
minor form), of the Cuban region. The large-flowered forms, on the other hand, to which the 
Antillares appear to be allied, include four related much differentiated groups: (a) Antillanae 
(14 species and three minor forms) of the Greater Antilles, (b) Bahamanae (6 species) of the 
Bahamas, (c) Caribaeae (15 species), of the Caribbees, and (d) Viviparae of the Leeward Islands 
(5 species) and of northern Venezuela (1 species). None of the species into which these groups 
are divisible, so far as now known crosses a 100-fathom barrier, however narrow, except as they 
might be understood to do so when heading the labyrynthine channels of the Bahamian banks. 
The characters and affinities of the groups are shown more clearly in a contrast of the species 
taken as typical of each than in any other form of analysis, as follows: 
