part 2] RUGOSE CORALS FROM THE BURUNDI SERIES. 167 



closely the Australian species than it does the British. In PL IX 

 are reproduced side by side for comparison longitudinal sections 

 of L. martini from Settle, England (fig. 5), L. stanvellense from 

 Roekhampton, Queensland (fig. 6), and C. columen (fig. 7). 

 Figs. 5 & 6 are twice and fig. 7 three times the natural size. 



The intermediate character of the Australian species is readily 

 observed. The Australian species of Litliostrotion to which 

 C columen most closely approaches in the size of its corallite is 

 L. arundineum Etheridge fil., which averages 4 to 5 mm. in 

 diameter. 



Locality. 



The holotype was found in Slaughterhouse Creek, near Grravesend 

 (N.S.W.); but an isolated corallite associated with the Dipliy- 

 jyhyllum mentioned on p. 168 was obbained from the parish of 

 Moorowarra, near Somerton (N.S.W.), The type-specimen was 

 originally a small group of corallites about 5 or 6 cm. long and 

 perhaps 1 cm. in cross-section. From this specimen a series of 

 sections have been cut. The type - material l is in the collection 

 of the Geological Survey of New South Wales ; but some sections 3 

 have also been deposited in the British Museum (Natural History). 



V. Lithostrotion Fleming, 1828. 



['A History of British Animals' p. 508. Genotype: L. striatum Fleming, 

 loc. cit.=Astraea basaltiformis Conybeare & Phillips, 1822, ' Outlines of the 

 Geology of England & Wales ' p. 359 ; = Madrepora vorticalis Parkinson, 

 1808, ' Organic Remains ' p. 45 & pi. v, figs. 3, 6 ; = Lithostrotion sive Basaltes 

 minus striatum et stellatum Lhwyd, 1699, ' Lithophylacii Britannici Ichno- 

 graphia ' p. 125 & pi. xxiii.] 



Compound coral; the corallum may be fasciculate or 

 massive, and accordingly the corallites are cylindrical or prismatic. 

 The number of septa and the complexity of structure are propor- 

 tional to the size attained by the particular ' species.' 



In the more typical forms of Litliostrotion the following 

 structures are to be found : — the septa are united to the epitheca ; 

 the major septa reach the columella, but the minor extend only a 

 short distance beyond the theca. The fossulae are inconspicuous. 

 The columella is usually well developed. The tabulse are also 

 generally well-formed conical plates, often extending from the 

 columella to the theca. The dissepiments are small, uniform, and 

 in large ' species ' build up a wide extrathecal area. 



The individual members of the genus exhibit, however, great 

 variation, and departure in one respect or another from the more 

 characteristic form is frequently found. 



A variation, common in the fasciculate colonies but rare in the 

 massive, is a shortness (as seen in transverse section) of all the 

 septa : the major as well as the minor extending inwards little 

 beyond the theca. There is no columella, and consequently the 



1 G. S. Reg. 1464. 



2 R 21999 & R 22000-01, each cut from the holotype. 



n2 



