no ECHINOIDEA. II. 



Suborder Amphisternata. 



Fam. Spatangidae. 



It may be expressly stated that by including here in the < familys Spatangida all the genera 

 mentioned in the following, viz. Aeropsis, Hemiaster, Schizaster, Spatangus, Echinocardium and Bris- 

 sopsis, besides some few others, as Accste, Pcriastcr which I have taken the opportunity to discuss, I 

 do not mean to maintain that all these genera do really belong to one and the same family. It is only 

 a provisional arrangement; so long as I have not studied more carefully all the recent genera of 

 Amphisternous Spatangoids, or at least so many of them as are available for me, I do not want to 

 give my view of their classification. I hope to be able to do so in Part II of the Siam-Echinoidea. 



Aeropsis noni. nov. 



The name Aerope by which Wyv. Thomson designated the curious Spatangoid described by 

 him in The Atlantic I. p. 381 was preoccupied and thus cannot be kept for the Spatangoid. It was 

 first used by Leach, though only as a Manuscript name, Ac rope bidens, for a crab of the genus 

 Macrophthalwms Latr. [Macr. parvimanus Latr.). 1 Later on, in i860, it was employed by Albers for a 

 pulmonate Gastropod of the Fam. Ilelicoidea [Aerope caffra; South Africa) 2 . It is thus beyond doubt 

 that the Spatangoid named Aerope in 1877 must have another name. I therefore propose the name 

 Aeropsis, which recalls the old familiar name so much that this change of name can scarcely give 

 much trouble. 



25. Aeropsis rostrata (Wyv. Thomson). 

 PI. V. Figs. S— 10, 15, 20, 22. PI. XV. Figs. 1 — 2, 5, S, 13, 19—21, 29, 37, 40, 43, 52. 



Synonym: Aerope rostrata Wyv. Thomson. 



Literature: A. M. Norman: Crustacea, Tunicata, Polyzoa, Echinodermata etc. Biology of the 

 « Valorous; Cruise 1875. Proc. Royal Soc. 25. 1876. p. 211. — Wyv. Thomson: The Atlantic. I. p. 381. 

 Fig. 99. ■- ■ A. Agassi/.: Challenger -Echinoidea. p. 192. PI. XXXIII. Figs. 6 — 13, XXXIII. a. 8—12, 

 XXXIX. 23, XLI. 7— 8. (Non.: PI. XXXIII. 1—5.) — Verrill: Results of the Explorations made by the 

 Steamer Albatross? off the Northern Coast of U. S. in 1883. (426). p. 539. 



In his description of this species Professor Agassiz points out that his specimens differ con- 

 siderably in outline, as is also very well seen in the figures given on PI. XXXIII of the Challeuger*- 

 Echinoidea. Nevertheless he does not regard them as different species, and in his recent work <The 

 Panamic Deep-Sea Echini (p. 194) it is maintained that the differences in outline of the specimen(s) 

 figured on the PI. XXXIII of the Challenger >-Echinoidea are all compatible with differences due to 



1 List of specimens of Crustacea in the British Museum. 1S47. p. 37. 

 -' Tryon: Structural and systematic Conchology. KS84. III. p. 18. 



