134 ON THE FOSSIL CORALS OP THE 



lAtJiostrotion only by the absence of the columella, and we have much 

 reason to think that the non-existence of that organ is here merely 

 accidental, and due to the process of fossilisation. The considerations 

 which induced Mr. Lonsdale to form this new generic division, were 

 founded upon the supposed fissiparous mode of multiplication of these 

 corals ; but after close examination of their structure, we are fully con- 

 vinced that they are not in reality fissiparous, and that the appearance 

 which at first sight may be taken for a fissiparous division of the 

 calice, is due to the rapid lateral coalescence of the young individual 

 produced by gemmiparity and the parental corallite."* 



The first of the two reasons given in this quotation for uniting 

 DipJiypJiyllum vrith Lithosfrotion is sufiiciently answered by the fact 

 that there are several species agreeing preciseljr with Lonsdale's figures 

 and descriptions in every other respect, which in numerous well pre- 

 served specimens exhibit no trace of a columella or central axis. The 

 second is well explained by the observations of Edwards and Haime, 

 who are of opinion that what appears to be a fissiparous gemmation 

 is in fact a species of calicinal budding. Upon this point our spe- 

 cimens throw much additional light. In the same group some of the 

 corallites have young ones budding from their sides, while others bifur- 

 cate, the two branches being equal in size to each other and to the 

 parent stem. The statement, therefore, of Lonsdale, that the species 

 examined by him appeared to be renewed by fission, is not sufficient 

 to warrant the suppression of the genus, it being in substance only an 

 erroneous view of one of the characters. 



The name of Diplojpliyllum was proposed by Professor Hall, in 

 1852, for some corals of the Niagara limestone, which have all the 

 characters of DvpJiypTiyllnm. Figures 1 m and 1 n Plat. 33, Pale. N. 

 Y., vol. 2, may be referred to as good representations of lateral bud- 

 ding and fiissiparous gemmation exhibited in the same corallites. 



DiPHYPHYLLTJM ARUNDINACEVM. — (BillingS.) 



Description. — Corallum forming large masses of long, cylindrical, 

 straight or flexuous stems, from three to four lines in diameter, some- 

 times in contact but usually distant from one to three lines from each 

 other ; radiating septa thin, between forty and fifty in number, rarely 



*Edwards and Haime. British Fossil Corals^ published by the Pateontographical 

 Society, p. 145. 



