H94 



THALLOPHYTES. 



L. annulus (fig. 1361, b) — which were originally described under 

 the name of Dactylopora. Existing forms of Larvaria are known, 

 and fossil types occur commonly in the Eocene Tertiary, often in 

 the form of separate segments of the calcareous cylinder. Dactylo- 

 pora, as now restricted, includes Eocene and Miocene types, and is 

 also closely allied to Cymopolia. Gyroporella (including Diplopord) 

 comprises types in which the skeleton has the form of a short calca- 

 reous cylinder (figs. 1361, e-g), from one to six millimetres in dia- 

 meter, with two or more rows of pores on each segment of the stem. 

 This genus begins in the Permian rocks, and is so enormously 



Fig. 1361. — A, Larvaria {Dactylopora) eruca (recent) magnified 30 diameters, and viewed from 

 the inner face ; b, Larvaria {Dactylopora) annulus, from the Eocene Tertiary, magnified 40 

 diameters, viewed in profile, and showing two superimposed rings ; c, The same viewed from 

 above and similarly magnified ; d, Part of the cylinder of Dactylopora reticulata (Tertiary), 

 viewed in profile, and similarly enlarged ; e, Fragment of Muschelkalk, with tubes of Gyroporella 

 cylindrica, of the natural size ; f, Transverse section of a tube of the same, enlarged 10 dia- 

 meters ; G, Vertical section of the same, enlarged 12 diameters. (Figs, a-d are after Carpenter ; 

 figs. E-G are after Giimbel.) 



developed in the Trias of Southern Germany and Switzerland as to 

 give rise to massive and widespread beds of limestone. A species 

 of this genus also occurs in great numbers in the Cretaceous series 

 of the Southern Lebanon Mountains. In the genus Ovulites, again, 

 the skeleton usually presents itself in the form of a small, ovoid or 

 clavate, calcareous body, enclosing a single chamber, with regularly 

 disposed superficial pores, and often perforated at both poles. Such 

 a body is really a single joint of the stem of the original plant. The 

 species of Ovulites are found in deposits of Eocene and Miocene 

 age. Lastly, in the genus Uteria, the skeleton consists of branched, 



