66 Mr. C. T. Regan on the Anatomy and 



Eocidaris scrobiculata (Sandberger). 



Fig. 5. Holotype. Interambiilacral. original of Sandberger, pi. xxxv. 

 fig."3. 



Miocidaris keyserlingi (Geinitz). 



(a) Specimens from the Zechstein of Possneck. 



Fig. 6. Greater part of an interambulacrum, interior view, showinjr 

 imbricate sutures, denticulation of adanibulacral margin, and 

 pcristomial structures. Brit. Mus. E. 11:^1. 



Fig. 7. Radiole, incomplete di.'«tally, longitudinally striate. Brit. Mus. 

 E. 14,104. 



Fig. 8. Interambulacral, to show nature of tuberculation. Brit. Mus. 

 E. 1121, on another part of the rock-fragment that bears the 

 original of tig. 6." 



(6) Specimens from the Magnesian Limestone of Tunstall Hill : 

 topotypes of Cidaris verneuilinna King. 



Fig. 9. Greater part of an interambulacrum, interior view, showing 

 denticulatiou of adambulacral margin and peristomial struc- 

 tures. 



Fig. 10. Interambulacral.'s, from theadapical region of a small individual, 

 showing slight interradial tubercuhition. 



Fig. 11. Interanibulacral from ambital region of a larger individual, 

 showing Well-marked scrobicular tubercles. 



Fig. 12. Interanibulacral from ambital region, with scrobicular tubercles 

 not distinguished from the dcns-e interradial tuberculation. 



FKg. 13. A similar interambulacral, with rather less interradial tubercu- 

 lation. 



Fig. 14. Radiole, subcylindrical, longitudinally striate, non-muricate. 



Fig. 15. Radiole, fusiform, murieate in longitudinal series. 



Fig. 16. Radiole, fusiform, murieate in transverse series. 



Fig. 17. Radiole, subfusiform, very slightly murieate. 



Figure? 1-5, representing Eocidaris, are enlarged 3 diameters. All are 

 based on photographs, but owing to the dark colour and obscurity of the 

 specimens the details have been emphasized. 



Figures 6-17, representing Miocidaris, are enlarged 6 diameters. 



Photographs by Mr. H. Herring. Drawings by Mr. G. T. Gwilliam 

 and Mr. A. H. Scarle, under the direction of the author. 



XI. — On the Anatomy and Classification of the Scombroid 

 Fishes. By C. Tate Regan, M.A. 



Most schemes of classification of the Teleostean fishes in- 

 clude a group Scombroidei or Scombriformes, comprising the 

 Scombridae and Carangidaj and a varying number of other 

 families supposed to be related to them. In Boulenger's 

 classification the Scombriformes form a division of the 

 Acanthopterygii, but it is admitted that no good definition 



