THE ANNALS 



MAGAZINE OF NATURAL HISTORY. 



[FIFTH SERIES.] 

 No. 24. DECEMBER 1879. 



XLV. — On the Structure of Astrophiura, a new and aber- 

 rant Genus of Echinodermata. By W. Percy Sladen, 

 F.L.S., F.G.'S. 



[Plate XX.] 



A brief summary of some of the structural peculiarities of 

 this abnormal Echinoderm was published last year (Proc. 

 Roy. Soc. vol. xxvii. p. 456) ; and subsequently a short note, 

 together with a specific diagnosis of the form, appeared in 

 Carus's ' Zoologischer Anzeiger,' Jahrg. ii. (1879), p. 10. 



It is the purpose of the present communication to furnish a 

 description in detail of Astrophiura permira, and to offer such 

 remarks upon its affinities and relationship as are naturally 

 suggested by the investigation. Some delay has intervened 

 in the publication of these observations, prompted chiefly by 

 the desire to obtain a further supply of material, in order to 

 give a more exhaustive description of the anatomy of the 

 organism ; but as such a wish may remain unrealized for 

 an indefinite period, it does not now seem desirable to with- 

 hold longer the present notes upon this interesting specimen. 



Astrophiura permira^ nobis. 



General Form. — The body is pentagonal and much de- 

 pressed, arched above and slightly concave beneath, suggesting, 

 at the first rough glance, a superficial resemblance to the 

 Asteriscus type of starfish. The test is entirely covered with 



Ann. & Mag. N. Hist. Ser. 5. Vol. iv. 29 



