THE ACTINIANS OF PORTO RICO. 
855 
McMurrich in 1896 (p. 182) described the Heteractis lucida of Duchassaing & Michelotti from 
specimens obtained from the Bahama Islands. The chief characteristic of the genus is the presence of 
tubercles upon the tentacles, and these are strongly marked in the West Indian representative. 
H. lucida is not uncommon in Jamaican waters, living under exactly similar conditions as Aiptasia 
annulata. When fully expanded the two are easily mistaken for one another, unless one is close 
enough to distinguish the character of the tentacular wall. The living polyps are found to he closely 
allied in such details as the peculiarities of coloration, the delicacy of the tissues, and inability to 
overfold on irritation. Internally the mesenterial musculature of H. lucida bears the closest resem- 
blance to that of A. tagetes and A. annulata, and the other general characters of the three are found to 
agree. It. is evidently best regarded as an Aiptasia, in which case the three Antillean species, A . tagetes, 
A. anmdata, and A. lucida, present an interesting gradation in connection with their tentacles. The 
wall is smooth in the first mentioned, and nematocysts are distributed throughout; in the second 
the tentacles bear incomplete annuli, which are really thickenings due to the aggregation of large 
nematocysts; and in the third species the annuli have, as it were, become shortened up and form 
spheroidal tubercles. McMurrich found a feeble mesoglceal sphincter muscle in his specimens of 
A. lucida, but I can not discover such in the Jamaican polyps. 
Aiptasia annulata (Lesueur). Pis. Ill, XI, XII, Figs. 11,41-44. 
Actinia annulata, Lesueur, 1817, p. 172. 
Dysactis annulata, Milne-Edwards, 1857, p. 202. 
Aiptasia annulata, Andres, 1883, p. 392; McMurrich, 1889, p. 7, pi. I, fig. 1: pi. Ill, fig. 1; Puerden, 1898a, p.457; Verrill, 1900, 
p. 556; pi. xvin, fig. 3. 
Actinia solifera, Lesueur, 1817, p. 173. 
Paradis ? solifera, Milne-Edwards, 1857, p. 249. 
Paradis solifera (Actinia) , Duchassaing et Michelotti, 1800, p. 39. 
Bartholomca solifera, Duchassaing et Michelotti, 1860, p. 133, pi. vi, fig. 14. 
Aiptasia solifera, Andres, 1883, p. 386. 
Many specimens of this species were collected from Porto Rico, thirty or forty coming from Guan- 
ica Bay, so that, it must be very abundant around the island. It is also common around Jamaica, and 
occurs in the more northern Bahamas and Bermudas. McMurrich has already given a full description 
of the Bahaman representative, but the specimens from Porto Rico and Jamaica present an important 
difference in the arrangement of the tentacles and mesenteries, to be referred to later. The description 
of the Porto Rican specimens given below is supplemented by notes on the living polyps as met with 
around Jamaica. 
External characters. — In the living condition the base is flat and very firmly attached to various 
objects on the sea-floor. It is slightly larger in diameter than the column, and thin-walled, the lines 
of attachment of the mesenteries showing through. The column is erect, smooth, cylindrical, and 
capable of much extension and retraction. The internal mesenterial attachments show through as 
distinct white lines on the darker ground, and divide thecolumn-wall into alternations of three narrow 
areas and a broader one; above, the mesenterial spaces are seen to be double those below. In pre- 
served specimens, and this applies to all the Porto Rican examples, the column is deeply constricted 
a little below the apex, as in the figure of the species given by Duchassaing & Michelotti (1866, pi. vi, 
fig. 14), and as is recorded by McMurrich for Aiptasia sp. (1889a, p. 102). Verrill figures a specimen of 
the closely allied A. tagetes in this condition. The upper part, of the column is altogether incapable 
of becoming overfolded on retraction of the polyp, so that the disk and tentacles are always visible. 
Four or more horizontal cycles of oval cinclidal apertures, at the apex of white tubercles, occur 
about the middle of the column. The cycles are usually incomplete or broken, pores being missing 
here and there. The number of apertures in a vertical row, corresponding with one mesenterial 
chamber, usually ranges from one to five or six, but in a Bahaman example McMurrich found twelve. 
White acontia are emitted in abundance through the cinciides and also through the mouth. Distally 
the column becomes' somewhat enlarged and passes directly into the tentacles, so that no definite 
columnar margin or fossa exists. 
The tentacles are marginate, very numerous, and arranged in many hexamerous cycles; as many 
as 192, or even more, may be present. They are non-retractile and strongly entaemseous, the inner 
being usually long, as much as 5 or 6 cm. On full extension the walls are thin and nearly transparent, 
with numerous incomplete thickened spirals or rings, usually along the whole length. In some of the 
