chief Generic Types of Palceozoic Corals. 65 



or less certainly, with G. patuluj Mich., C. cornu-copice, 

 Mich., C. punctata, D'Orb., G. ibicina, Lonsd., and G. 

 hilateralis, Hall ; whilst G. cornu-hovis, Mich., is apparently 

 an Amplexiis, and G. sulcata, D'Orb., is an Aulacophyllum. 

 These distinguished authorities, therefore, consider that Ga- 

 ninia, Mich., is but a synonym of the previously founded 

 Zaphrentis of Rafinesque and Clifford ; and in this opinion 

 they have been generally followed. 



Prof. M'Coy, on the other hand, came to the conclusion 

 that Ganinia could be separated from ZapTirentis by the pos- 

 session of a circumferential zone of vesicular tissue ; but his 

 conclusion was vitiated by the fact that he included under this 

 name forms of very diverse nature. Thus liis G. turhinata 

 and G. lata are referable to Omphyma • wliilst his G. sub- 

 ibicina appears to be a Zaphrentis. 



The genus Gyathopsis, D'Orb., again, was considered by 

 Milne-Edwards and Haime as synonymous with Arnplexus ; 

 but it was retained as distinct by M'Coy, who placed under it 

 C. cornu-hovis,M.\Qh. (PI. VII. figs. 6, 6 a), which is pro- 

 bably an Amplexus, together with C. cornu-copice , Mich., and 

 G. funyiies, M'Coy, both of which belong to Zaphrentis. 

 According to M'Coy's definition, Gyathopsis, D'Orb., is di- 

 stinguished by not having the exterior zone of vesicular tissue 

 which is present in Ganinia ; whilst it is said to differ from 

 Amplexus chiefly in the more vesicular nature of the tabulae, 

 and the greater inward extension of the septa. 



More recently Dybowski {ojj. jam cit.) has declared in 

 favour of retaining both Ganinia and Gyathopsis. He places 

 Ganinia in the immediate neighbourhood of Omphyma, from 

 which it is separated, in his opinion, solely by the fact that it 

 possesses but a single septal fossula, whilst four such exist in 

 the latter. He also retains Gyathopsis, D'Orb. (as distinct 

 from Amplexus), and places it next to Zaphrentis, from which 

 he separates it simply by the smaller development of the septa. 

 According to his views, Zaphrentis and Gyathopsis agree with 

 one another in having septa of unequal lengths and of irregular 

 arrangement ; whereas he places Amplexus in a different 

 family, as having equal and regularly arranged septa. We, 

 however, do not think that any difference in the extent to 

 which the septa are developed should, of itself, be regarded as 

 of such high value in classification ; nor can we admit, as a 

 matter of fact, that the septa in the genus Amplexus are always 

 equally developed. 



Upon the whole * there can be little hesitation about con- 



* Whether Ci/athopsis, D'Orb., can be retained as a distinct genus or 

 not depends, of course, upon the characters possessed by the form which 

 Ann. & May. N. Hist. Ser. 4. Fo^. xvii. .5 



