HILL: GEOLOGY OF JAMAICA. 249 
little more than a millimeter apart, but the average is as first stated. The 
calices on the upper side are not at all elevated above the ccnenchyma, but on 
the lower side they stand about 1 mm. above it. The outside of the projeeting 
part of the corallite has distinet equal costeo corresponding to each septum. I 
observed no perforations between the coste. The comenchymal surface is 
densely and minutely granulate; when the outer surface is worn away its 
porous nature is revealed. Septa : there are six septa larger and more prominent 
than the others; in each well preserved calice examined, between each pair of 
larger septa is a pair of smaller sepia. The septa are stout, so far as could be 
made out solid, imperforate, and have entire margins. There is no columella. 
Locality. Near Cambridge Station, south of Montpelier, St. James Parish, 
Jamaica (R. T. Hill, collector). 
Types. Museum of Comparative Zoölogy, Harvard University. 
Remarks. This species has considerable resemblance to Dendracis haidingeri, 
Reuss, from Oberburg, Steiermark,! also found at Castel Gomberto, Monte 
Grumi and Monte Viale, Italy. Felix? reports it from Gebel Auwébet, Egypt. 
The following notes made on specimens in the Vienna Hofmuseum show the 
differences. The calices of D. haidingeri tend to be constricted above. There 
are two complete cycles of septa, with members of the third cycle sometimes 
present. On the lower side of the projecting part of a corallite there are two or 
more coste for each septum. 
PORITES, Lamaror. 
Porites reussiana, Duncan. 
1865, Porites reussiana, Duncan, Quart. Jour. Geol. Soc. London, Vol. XXI. p. 8 
(original description), Pl. I. Fig. 2. Another reference, p. 7. 
1868. Porites reussiana, Duncan, Quart. Jour. Geol. Soc. London, Vol. XXIV. 
p. 25. 
Original Description. “The corallum is in more or less cylindrical branches, 
which leave the stem at an acute angle, and are often flattened, and alwavs 
rugged and gibbous. The calices are large, irregular in size, and shallow. The 
columella is small, and there are sometimes more than six distinet pali. The 
septa are from eight to twenty-four in number. Diameter of calices often 
ty inch; that of the branches from 4f to H inch. 
* Locality. Upper Clarendon District, Jamaica.” 
I saw the type in the collection of the Geological Society of London, and add 
a few notes to the above description, The usual number of cycles of septa is 
1 Denkschrift d. Wiener Akad. d. Wissenschaft. (Mat. Natur.), Bd. XXIII. 1st 
Abtheil, 1863, p. 27, Pl. VIII. Figs. 2-6. 
2 Felix, Zeitschrift d. deutsch. geolog. Gesellschaft, 1884, Bd. XXXVI p. 424, 
PI. III. Fig. 12. 
aeneus cov ass inet as 
