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-costse are directly con- 

 tinuous from one calice to the other, and there is no indication of any sort of 

 bounding wall between the calices. The 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 trabeculse, 

 which are slightly inclined inward. The upper terminations of the trabecule 

 make the knots on the septal margins. The fusion of adjoining trabeculae is 

 a^tparently complete, so the septa are solid except occasionally just below 

 their upper margins. Synapticulae are abundant. No dissepiments were seen. 

 Calices wide open, not very deep. In the columella space are a few papillae. 



Locality. Catadupa (R. T. Hill, collector). 



Tij'pe. Museum of Comparative Zoology, Harvard University. 



RemarJcs. 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 Thamnastrcea, because no 

 thorough study of the type of the latter genua, Thamnastrcea dendroidea 

 (Lamouroux), has been made. Pratz in his memoir, " Ueber den Aufbau des 

 Septalapparates einiger charakteristischer Gattungen," ^ 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 Thamnastrcea 

 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 Thamnastrcea 

 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 whether it is a 

 ThcLinnastrcea. The following is Pratz's definition of Mesomorpha : ^ " Polypar 

 massiv, knollig, hockrig oder iistig, zuweilen incrustirend. Kelche niedrig, 

 nicht durch scharfe Grate umschrieben, sondern durch Septocostalradien 

 untereinander verbunden. Eine mauer fehlt oder ist hochtens rudimentar 

 und von den Septocostalradien versteckt. Septa compact, an den Seitenflachen 

 mit Kornern versehen. Die benachbarten Septalflachen sind durch starke, 

 echte Synaptikeln mit einander verbunden. Letztere verleihen dem zwischen 

 den Kelchcentren befindlichen Sclerenchym bei unregelmassigem Verlaufe des 

 Septocostalradien zuweilen ein Coenenchym-artiges Aussehen. Der Septalrand 

 ist regelmjissig gekornelt und deutet auf einen trabeculiiren Aufbau bin. 

 Siiulchen papillar haufig mit mehreren Sternleisten verschmolzen." There 



1 Ueber die verwandschaftlichen Beziehungen einiger Korallen Gattungen. 

 ralaeontograpliica, 1882, Bd. XXIX. pp. 92-98. 



^ Eocane Korallen aus der Libyschen Wiiste und Aegypten, Palaeontographica, 

 Bd. XXX., 1883, Pal. Theil, pp. 22G-227, PI. XXV. Figs. 45,45a. 



2 Eoc. Korall. aus der Lib. Wiiste, etc., loc. cit. 



