Prof. Garwood — Calcareous Algce. 549 



Pusulina Limestone of the Velebit district in Dalmatia, while later, 

 in 1912 (Vevh. d. k. k. geol. Reichsanstalt, 1912, p. 330), he records 

 further examples of these genera from specimens, collected by Koch, 

 of rocks of the same age in Croatia. The same genera have also been 

 recorded by Xarpinsky f rom the Fnsulina Limestone of Japan (Yerh. d. 

 Euss.-kais. Min. Gesell. St. Petersb., ser. ii, Bd. 46, 1908, p. 257, pl.iii). 

 Still more recently another form of Girvanella has been described 

 by Yabe from the (?) Carboniferous rocks of San-yu-tung and other 

 localities in China under the name of G. sinensis} 



Permian and Trias. 



In Britain I have met with no reference to the presence of 

 Calcareous Algse in rocks of this period, but quite recently 

 Mr. Cunnington, of H.M. Geological Survey, sent me a few nodules 

 from the base of the Permian near Maxstoke ; in thin sections they 

 resemble very closely specimens of Spongiostroma from the Carboni- 

 ferous Limestone described above. 



On the Continent masses of limestone, composed almost entirely of 

 remains of Diplopora and Gyroporella, have long been known from 

 the Muschelkalk and Lower Keuper beds of the Eastern Alps, notably 

 the Mendola Dolomite, the Wetten Limestone of Bavaria, and from 

 similar horizons in Tyrolian Alps. In the Lombard Alps the same 

 facies reappears, and Diplopora annulata occurs abundantly in the 

 well-known Esino Limestone above Varenna, while recent work by 

 Cayeux(C. R. Acad. Sci., Paris, tome clvii, p. 272, 1911, and Exploiation 

 Arch, de Delos, Paris, vol. iv, pt. i, 1911), Negris (C. E.. Acad. Sci., 

 Paris, tome civ, p. 371, 1912), and Benz (('entralb. f. Min., 1911, 

 pp. 255, 289, and ibid., 1912, p. 67 ; also Jahrb. osterr. geol. B. A., 

 Ix, pt. iii, p. 451, 1910) on the Triassic rocks of the mainland of 

 Greece and the Cyclades shows the wide distribution of the Algal 

 limestones in the south and south-east of Europe. 



In 1891 Bothpletz ^ showed that certain spherical bodies in the 

 Triassic beds of St. Cassian, formerly regarded as oolitic structures, 

 were in reality algal growths, and referred them to a new genus, 

 SphcBrocodiiim, on account of their apparent resemblance to the living 

 form Codium. He describes them as encrusting organisms forming 

 nodules up to several centimetres in diameter. They contribute 

 substantially to the rocks in which they occur, and are found 

 especially in the Baiblkalk, the Kossenerkalk, and the Plattenkalk. 



JUKASSIC. 



The Mesozoic rocks of Britain contain but few examples of marine 

 algal limestones, and important occurrences are confined to the Jurassic 

 rocks. The forms met with are limited to two genera, Girvanella 

 and Solenopora. 



Tubes of Girvanella occur fairly abundantly in the British Oolites, 

 especially in the well-known Leckhampton Pisolites, andMr. Wethered, 

 who has made a special study of oolitic structures, appears inclined 

 to refer all oolitic structures to organic agency of this nature. 



■^ H. Yabe, Science Eeports of the Tahoku Imp. Univ., ser. n, Geology, 

 vol. i, No. 1, Japan, 1912. 



2 Zeitsch. d. deut. Geol. Ges., vol. xliii, pp. 295-322, pis. xv-xvii, 1891. 



