GENERA AND &KOUPS OF THE ECHINOIDEA. 306 



SUPPLEMENTAEY NOTE. 



The following Note was written during the printing of this " Revision " 

 (Oct. 16th, 1889). 



An important work came to hand after the reading of this " Revision," and 

 the following are necessary remarks: — 



Explorat. Sci. de la Tunisie, Ech. Foss., 1889, MM, Thomas et V. Gauthier. 



Genus Opisopneustes, Gauthier, 1889, p. 2. This, according to the system 

 adopted in this "Revision," is a subgenus of Hemiptieustes. 



There is not sufficient structural difference between Holaster and a genus 

 Pseudholaster, Pomel, 1883, adopted by M. Gauthier, and the first-named 

 genus absorbs the other. 



Plesiasier, Pomel, adopted by M. Gauthier (p. 26), is said to be a Micraster 

 with a peripetalous fasciole ; but, considering the shape and the distribution of 

 the species of Metalia from Sind, and the existence of the genus Meoina, it is 

 impossible to recognize the proposed genus without further knowledge about 

 the anatomy of the test. 



Had M. Gauthier had the advantage of seeing the great collection of species 

 of Plesiolampas, Duncan and Sladen, from Sind, he would have placed his 

 genus Hypopygurus in it. There is no distinction. 



Pygopistes, Pomel, 1883, admitted by M. Gauthier, comes within Catopygus 

 (see ante, p. 185). Parapygus, Pomel, is inseparable from EcMnanthus. 



Genus Adelopneustes, Gauthier, 1889, op. cit. p. 52, is a good and most 

 interesting genus belonging to the Echinoconinse. It has the characters of 

 Echinoconus, but the ambulacral plates are few, high, and single, and each has 

 a pair of very small pores. Cretaceous ; Tunis. 



Bachiosoma, Pomel, 1883, is a Cyphosoma. 



Thegaster, Pomel, 1888, when compared with fossil and recent Fihularics (see 

 especially the tumid forms described by A. Agassiz), clearly is a true Fibularine, 

 and synonymous with Fibularia. 



Pliolampas, Gauthier?, op. cit. p. 97, appears to be ^Palmolampas, Bell, with 

 a produced rostrum and periproct. 



Orthechinus, Gauthier, p. 105, admirably described, covers the same ground 

 as Thylechinus, Pomel (amended), see p. 89 of this "Revision." M. Gauthier's 

 generic name is the best. 



Subgenus Badiocyphus, Ootteau, 1888 (genus), Oompt. Rend, de I'Acad. des 

 Sci. vol. 107, is a subgenus oi AGantheohinus (see ante, p. 289) with perforate and 

 crenulate tubercles. 



LINN. JOUEN. — ZOOLOGY, VOL. XXIII. 20 



