hill: geology of Jamaica. 233 



DESCRIPTION OF SPECIES. 



TROCHOSMILIA, Edwards axd IIaime. 

 Trochosmilia hilli, 8p. nov. 



Plate XXXVI. Figs. 1-4. 



Form irregularly cyatliiform, with a stout thick pedicel about one half the 

 length of the corallum. Height of corallum about 22 mm. The calice oval, 

 with a slightly sinuous outline. Greater diameter 23.5 mm. ; diameter at 

 right angles to the greater, in the plane containing the vertical axis, 15.5 mm. 

 The costse are very fine, alternating in size, with beaded margins, as shown in 

 Figure 3, Plate XXXVI. The crowded, very fine, beaded costse appear to be 

 splendid specific characters. Septa very numerous, thin and crowded. One 

 hundred and ninety septa were counted in the type. The systems and cycles, 

 probably due to the irregular transverse outline of the calice, are not distinctly 

 differentiated, but there appear to be six complete cycles. The total number 

 of septa for a calice with six cycles is 192. The septal margins are not dentate, 

 but there are striations extending across them perpendicular to the flat planes 

 of the septa. The calicular fossa is rather shallow, the calice being wide 

 open, with a small depression in the centre. No columella; the edges of the 

 principal septa meet in the axial space. 



Locality. Catadupa, Jamaica (collected by R. T. Hill). 



Type. Museum of Comparative Zoology. 



Remarks. This species bears considerable resemblance to the Trochosmilia 

 acutimargo of Reuss, from the Eocene of Monte Grumi, near Castel Gomberto, 

 and Monte Carlotta,^ Northern Italy. I would call especial attention to the 

 specimen figured in Vol. XXVII. of the Denkschriften of the Vienna Academy 

 of Sciences.'^ 



I had the opportunity to study the original figured specimen of this form 

 in the University of Vienna geological collections. The chief difference 

 between the two species seems to consist in the difference in the character of 

 the costa3. The costse of acutimargo are acute or moderately rounded, while 

 in Mill the sides of the costge are perpendicular to the wall of the corallum. 



1 Denksclirift d. Wiener Akad. d. Wissenschaft Mat. Naturhist. 01., 1868, Bd. 

 XXVIII , Plate I. Fig. 1. Denkschrift d. Wiener Akad. d. Wissenschaft Mat. 

 Naturliist. CI., 1874, Bd. XXXIII., pp. 26, 27, Plate XLIII. Figs. 3-7. 



2 In tills volume, page 139, Reuss calls this species Trochosmilia profunda, but 

 later, in Vol. XXXIII. of the same series of publications, he shows that he had at 

 first confused two species under the name profunda, and separates the forms into 

 T. profunda and T. acutimargo, Plate I. Fig. 1, Vol. XXVIII., taking the latter 

 designation. 



