28 MADREPORARIA. 
surface, dense and finely echinulate, and the wall finely striate. This condition may perhaps 
be due to secondary deposition of lime. 
In the description of this and the preceding variety I have endeavoured to give the leading 
characters of comparatively typical specimens; but it must be understood that numerous 
intermediate forms occur which it would be difficult to allocate satisfactorily. The forms 
described by Ehrenberg as M. /ava and M. regalis appear to correspond roughly with M. pro- 
lifera and M. cervicornis, Lamk., though in some respects both show intermediate characters. 
Klunzinger instituted the name M. superba for the former, and pointed out that, although 
Ehreuberg’s type is recorded as from the Red Sea, the specimen had attached to it a specimen 
of Trochus imbricatus, Gmel., which is a West-Indian shell, and that therefore the recorded 
habitat is probably not correct. A specimen in the Berlin Museum, from Hayti, agrees very 
closely with the type specimen of M. regalis. After a careful comparison of the types of 
Lamarck and Ehrenberg with the fine series of West-Indian and other specimens in the 
British Museum, I have been unable to recognize any constant characters by which the 
species may be distinguished from one another. It has therefore seemed advisable to regard 
all as variations of one species, common to the Atlantic and Indo-Pacific Oceans. Pourtalés 
has pointed out, with regard to the West-Indian specimens of palmata, cervicornis, and 
prolifera, that the proper habit and robustness of each form is associated with a different 
position on the reef. M. palmata grows in situations exposed to the force of the sea; 
M. cervicornis in less exposed localities; whilst, for its full development, M. prolifera appears 
to require sheltered spots on the inner side of the reef. The form M. palmata, Lamk. 
(including the various synonyms), is uswally readily distinguished from all the others by its 
habit. Of the arborescent varieties, M. prolifera, Lamk., M. superba, Klz., M. regalis, Ehrb., 
and M. cervicornis, Lamk., form a consecutive series in which the habit gradually becomes 
more erect, the branches stouter, and the corallites relatively shorter. 
The specimens hitherto recorded under the various names included in the synonymy, 
beginning with Lamarck, nearly all come from the West Indies. The doubtful origin of 
Ehrenberg’s specimens has already been alluded to. Dana’s type of M. alces is queried 
from the East Indies, as was also the specimen figured by Rumphius to which he refers. 
Briiggemann’s Rodriguez specimens do not appear to me referable to that species; and the 
specimen recorded by Ortmann from Panama does not differ materially from alciform 
specimens of M. palmata from the West Indies; added to which Dr. Ortmann informs me 
that the habitat is not certain. On the other hand, Mobius has recorded the form 
M. superba, K1z., from Mauritius, and Faurot has recently obtained the same variety from 
the Gulf of Aden. Some of the specimens from Singapore, referred by Ortmann to 
M. secunda, Dana, appear to me to agree closely with West-Indian specimens of M. cervi- 
corns, Link., and, indeed, are the only specimens I have seen from the Indo-Pacific Ocean 
in other collections which do so. The most frequent Indo-Pacific variety appears to be 
M. superba, Klz., or M. regalis, Bhrb.; but a shallow vasiform specimen of M. palmata is in 
the collection of the British Museum. Several specimens of this species were collected by 
Mr. Saville-Kent at Thursday Island &. One specimen is almost identical with a West- 
Indian specimen of M. cervicornis in the British Museum, and a plate-like form with confluent 
branches also occurs there. Thus the three chief varieties of the species occur both in the 
Atlantic and Indo-Pacific Oceans ; but apparently they are nowhere so abundant as in the 
West Indies. 
West Indies and Indo-Pacific Ocean (Red Sea to Tahiti). 
