n 



in form from their liaviug grown attached to a spiral shell which was 

 inhabited by parasitic Crustacea. I have specimens showing all the 

 grades of change, from the nearly normal conical form of the genus 

 to the truncated form which has been described as the type of the 

 genus Heterocyathus. This form was well-described by Spengler in 

 * Nova Acta Hafnise,' i. 240, and noticed by Gmelin under the name 

 oi Madrepora Cochlea, p. 3/63. 



Messrs. Milne-Edwards and Haime described two species of this 

 genus under the names of H. tequicostatus, t. 10. f. 8, and//. Rous- 

 scBanus, t. 10. f. 9. Of the former he appears only to have seen a 

 single specimen. We have in the British Museum three very distinct 

 species, which may be thus described : — 



1. H. Cochlea = Mad. Cochlea, Gmelin, S. N. H. cequicostatus, 



Milne-Edwards and Haime, 324. t. 10. f. 8. {Radiata, PI. II.) 

 Coral subcylindric, hard, white, with narrow, equidistant, distinct 

 grooves, crenulated on the edges ; base rather dilated ; laminae nar- 

 row, sharp-edged, very unequal, grooved on each side, and with 

 crowded columns in the centre of the star. 

 Hab. Chinese Seas. 

 The holes on the outer surface are large and distinct. 



2. H. HEMtsPH^RiCA. {Radiata, PI. II.) 



Coral subcircular, depressed, subhemispherical, nearly flat below, 

 regularly convex above ; sides romided ; plates of star broad-topped, 

 as if truncated, covered on top and sides with very numerous crowded 

 spines and tubercles ; centre of star roundish, with small columella. 



Hab. Chinese Seas. 



The plates of this species resemble those figured as belonging to 

 H. Roussceamis, I. c. 325. t. 10. f. 9 ; but the shape of all the two 

 specimens in the Museum, which are nearly similar, is quite distinct 

 from the view of the side of that species. 



3. H. EUPSAMMiDES. {Radiata, PI. II.) 



Coral polymorphous, base flat, sides shehing, sinuous, surface 

 covered with very close, irregular, sinuous, denticulated ridges, and 

 pierced with numerous minute pores ; star irregular, compressed or 

 sinuous ; laminae narrow, then cribellated on the surface, and with an 

 oblong, elongated, convex, cribellated centre. 



Var. star more or less contracted in the centre, forming two more 

 or less distinct roundish stars. 



Hab. Chinese Seas. 



This species is immediately known from the former by the pecu- 

 liarity of the surface, which is like that of Caryophyllea ramea, and 

 by the convex elongated form of the centre of the star. 



I have described these three species together on account of their 

 having the same form and habit, but the structure of the surface and 

 the great diff'erence in the form and conformation of the stars induce 

 me to believe that they probably belong to three very distinct families 

 of corals. 



Since I described these corals I have shown the two latter species 

 to M. Milne-Edwards, who states that they had not before come 

 under his observation. 



