876 PROF, S. J. HICKSON ON THE 



PiATE xcri. 



Pig. 12. Upper view of skull of Dicynodon latieeps Broom. yV i^^*- ^'^e. 



Fig'. 13. Under view of snont of Dicynodon latieeps Broom. y\ nat. size. 



Fig-. 14. Side view of skull of Dicynodon lutriceps Broom. fV n^t. size. Tlie 

 contact between the front part of the skull and the occiput is missing, 

 but the relation of the parts must be almost as restored. 



Fig. 15. Upper view of skull of Dicynodon lutriceps Broom. About y^ nat. size. 



Fig. 16. Palatal view of skull of Dicynodon lutriceps Broom. About -y^ nat. size. 



Fig. 17. Upper view of skull of Dicynodon 'psittacops Broom. About ^ nat. size. 



Plate XCIII. 



Fig. 18. Side view of skull of ISndotliiodon whaitsi Broom. About f nat. size. 

 Fig. 19. Upper view of lower jaw of JSndothiodon platyceps Broom. About ys 



nat. size. 

 Fig. 20. Upper view of skull of JUmydops minor Broom. ^ nat. size. 

 Fig. 21. Side view of skull of Frodicynodon heaufortensis Broom. About xq nat. 



size. 

 Fig. 22, Upper view of skull of Ictidopsis elegans Broom. % nat. size. 

 Fig. 23. Side view of left dentary of Nytliosaurus browni Broom, f nat. size. 



53. On the Hydrocoralline Genns, Errina. By Professor 

 S. J. HiCKSON, F.R.S., F.ZS., The University of 

 Manchester. 



[Received April 29, 1912: Read June 4, 1912.] 



(Plates XOIV.-XCVI.) 



Index. ^i 



Page 



Revision of the genera ISrrina, iMhiopora, 



Spinipora 877 



Description of new species 882 



Notes on the structure of JSrrina novce zelandice , 884 



Note on geographical distribution 886 



Description of old species 887 



General remarks on structure 891 



List of known species 893 



Additional notes 894 



Literature 894 



Explanation of the Plates 895 



Four years ago Professor Benliam sent to me some specimens 

 of Stylasterina from New Zealand, with a request that I would 

 name them for him. At the same time he forwarded some notes 

 and drawings which have proved to be of considerable assistance 

 to me in working out their details, I am also indebted to 

 Professor Dendy for the loan of another specimen also from New 

 Zealand ; to the late Mr. Morgan, of Worthing, for the loan of a 

 specimen from an unknown locality; and to Mr. Gilchrist for 

 a specimen from the Cape of Good Hope. 



All these specimens clearly belong to one of three genera, 

 Errina, Lahiopora or Spinipora, as they exhibit the characters 

 that these genera exhibit in common a.nd by which they can be 

 separated from other Stylasterina. These characters are : (1) a 



