876 PROF. S. J. HICKSON ON THE 



PiATE xcri. 



Fit?. 12. Upper view of slcull of Dicynodon laticeps Bvoom. -^ "^*- ^i*^®* 



Fit?. 13. Under view of snont of Dicynodon laticeps Broom. y\ nat. size. 



Fig'. 14. Side view of skvill of Dicynodon lutriceps Broom. f% nat. size. The 

 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 hdriceps Broom. About jV nat. size. 



Fig. 16. Palatal view of skull of Dicynodon lutriceps Broom. About yg nat. size. 



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



Plate XCIII. 



Fig. 18. Side view of skull of HJndotJiiodon wJiaitsi Broom. About f nat. size. 

 Fig. 19. Upper view of lower jaw of JEndotliiodon platyceps Broom. About fV 



nat. size. 

 PMg. 20. Upper view of skull of JUmydops minor Broom, f nat. size. 

 Fig. 21. Side view of skull of Frodicynodon heaiifortensis Broom. About j'f, nat. 



size. 

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

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



53. On the Hydrocoralline Genns, Errina. By Professor 

 S. J. HiCKSON, F.R.S., F.ZS., The University o£ 

 Manchester. 



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



(Plates XOIY.-XCYI.) 



Index. 



Revision of the genera JSrrina, Ziahiopora, 



Spinipora 877 



Description of new species 882 



Notes on the structure of Errina 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 Benham 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 cleai'ly belong to one of three gener-a, 

 Errina, Lahiopora or Spi7iipora, as they exhibit the characters 

 that these genera exhibit in common and by which they can be 

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



