HILL: GEOLOGY OF JAMAICA, 247 
ring and the second ring of calices is from 3 to 5 mm. The distance between 
calices in the second ring is usually 3 mm. The septo-coste are directly con- 
tinuous from one calice to the other, and there is no indication of any sort of 
bounding wall between the calices. "Ihe septa are thick, very close together, 
the number in the larger calices is twenty-nine to thirty. There is considerable 
anastomosing between them. The margins are formed by series of roundish 
or squarish knots. The septa are composed of ascending moniliform trabeculeo, 
which are slightly inclined inward. The upper terminations of the trabecule 
make the knots on the septal margins. The fusion of adjoining trabecul® is 
apparently complete, so the septa are solid except occasionally just below 
their upper margins. Synapticule are abundant. No dissepiments were seen. 
Calices wide open, not very deep. In the columella space are a few papilla. 
Locality. Catadupa (R. T. Hill, collector), 
Type. Museum of Comparative Zoólogy, Harvard University. 
Remarks, The generic determination of this species, and also one already 
mentioned as coming from the Midway (basal Eocene) beds of Alabama, has 
given me enormous trouble. There is no way of distinguishing from the 
literature the difference between Mesomorpha and Thamnastrea, because no 
thorough study of the type of the latter genus, Thamnastrea dendroidea 
(Lamouroux), has been made. Pratz in his memoir, * Ueber den Aufbau des 
Septalapparates einiger charakteristischer Gattungen,” 1 does not even mention 
the type species. So, although Pratz has added some interesting observations 
on the septal structure of some corals, he has not informed us what Thamnastrea 
really is. He has not given the name of the species on which he based his 
figures and. studies, therefore we do not know that he studied Thamnastrea 
at all. 
According to Pratz’s figure of Mesomorpha;? apparently the species under con- 
sideration must belong to that genus, but it is impossible to decide whetherit is à 
Thamnastrea, The following is Pratz's definition of Mesomorpha:® * Polypar 
massiv, knollig, höckrig oder ástig, zuweilen inerustirend. Kelche niedrig, 
nicht dureh scharfe Grate umschrieben, sondern durch Septocostalradien 
untereinander verbunden. Eine mauer fehlt oder ist hóchtens rudimentür 
und von den Septocostalradien versteckt. Septa compact, an den Seitenflächen 
mit Körnern versehen. Die benachbarten Septalflachen sind durch starke, 
echte Synaptikeln mit einander verbunden. Letztere verleihen dem zwischen 
den Kelehcentren befindlichen Selerenchym bei unregelmässigen Verlaufe des 
Septocostalradien zuweilen ein Coenenchym-artiges Aussehen. Der Septalrand 
ist regelmässig gekörnelt und deutet auf einen trabeeulären Aufbau hin. 
G 
Säulchen papillär häufig mit mehreren Sternleisten verschmolzen.” There 
1 Ueber die verwandschaftlichen Beziehungen einiger Korallen Gattungen. 
Palaeontographica, 1882, Bd. XXIX. pp. 92-98. 
2 Eocäne Korallen aus der Libyschen Wüste und Aegypten, Palaeontographica, 
Bd. XXX., 1883, Pal. Theil, pp. 226-227, Pl. XXV. Figs. 45, 45 a. 
3 Eoc. Korall. aus der Lib. Wüste, etc., loc. cit. 
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