1887.] ON THE PAIRED FINS OF CERATODUS. 3 



Mr. Tegetemier exhibited and made remarks on some heads of the 

 Suraatran Rhinoceros {Rh. sumatrensis), male, female, and young, 

 forwarded from Sarawak, Borneo, by Mr. Brooke-Lowe. 



Prof. Bell exiiibited a specimen of Nereis pelagica which he had 

 received from his excellent correspondent Mr. R. L. Spencer of 

 Guernsey, and which was remarkable for the bifid arrangement of 

 tiie posterior portion of the body. He remarked that although Mr. 

 Robertson, of Oxford, Dr. Horst, and himself had put on record 

 Lumbrici with trifid ends, which probably were not really uncommon, 

 he had not been able to find any record of a similar condition in a 

 Polychsete. 



A communication was read from Messrs. H. B. Brady, F.R.S., 

 AV. K. Parker, F.R.S., and T. Rupert Jones, F.R.S., containing an 

 account of the Foraminifera procured on the Abrohlos Bank during 

 the cruise of H.M.S. ' Plumper ' in 1857. 



This memoir will be printed in the Society's ' Transactions.' 



The following papers were read : — 



1. On the Skeleton and Affinities of the Paired Fins of 

 Ceratodus, with Observations upon those of the Elasjno- 

 branchii. By G. B. Howes, F.Z.S., F.L.S., Assist. Prof, 

 of Zoology, Normal School of Science and Eoyal School 

 of Mines, S. Kensington. 



[Received December 14, 1886.] 

 (Plates I.-III.) 



Contents. V&efi 



I, Introduction 3 



II. Ou the Structure of the Ceratodus Fins in general and of the Pelvic 



Fins in particular 4 



III. On the Pectoral member of Ceratodus compared with the Pelvic one 



of the same and the Pectoral one of the Plagiostomes 11 



IV. On the proximal Postaxial Elements of the Ceratodus Pelvic Fin ... 16 

 V. On the Morphology of the Axis of the Ceratodus Fin 18 



VI. On the. Homologies of the Chimieroid Fin-skeleton, as compared 



with that of Ceratodus 22 



VII. Conclusions 24 



VIII. List of Authorities referred to 24 



IX. Description of the Plates (I.-III.) 26 



I. Introduction. 



I have lately described (17, p. 277) the vertebral column of a 

 Frog in connexion with which there had taken place, under disloca- 

 tion of the urostyle, a process tantamount to that of reproduction of 



a lost part. While searching for literature bearing upon this subject, 



1* 



