DESCRIPTION OF CHALK CORALS. 265 
those in the ‘ Exposition Méthodique,’ wanting altogether prominent, solid ridges, 
and being beset with numerous small tubercles, not a trace of which is delineated 
by Lamouroux, nor is the structure noticed in his account of the fossil, the 
specific name being apparently derived from stunted branches, which bear, in 
the natural size figure, the semblance of large spinous projections. M. Michelin, 
moreover, in his remarks upon the coral represented by him, no doubt with 
great accuracy, says, ‘‘ Ce polypier et le suivant ne nous paraissent pas avoir une 
grande analogie entre eux ;”’ and he adds, ‘‘ Nous nous réservons, lorsqu’un plus 
grand nombre d’échantillons de lespéce en discussion sera connu, d’adopter 
plutét pour elle le genre Neuropora, créé par M. Bronn ;” 
being among his own synonyms for Chrysaora spinosa. A comparison of M. 
Michelin’s figures with the delineation of Mr. Dixon’s coral (figs. 39, 39 a) will esta- 
blish an identity in two particulars,—1st, in the general character of the tubular 
Neuroptera spinosa 
apertures ; and 2ndly, in each having small spinous projections ; if also in the 
former ramifying ribs occur as in the Chrysaora spinosa of Lamouroux, another 
analogy would exist, and the absence of wart-like protuberances would be the 
only visible distinction. The two latter structures are however not considered 
generic characters, being of irregular or uncertain occurrence, and therefore not 
essential components. Mr. Dana’ regards ‘“ tubercles” likewise as hardly a 
character of generic importance, in his observations on Spinopora. Under these 
circumstances the choice of a term or genus was somewhat arbitrary ; but it was 
believed, that Neuwropora should not be adopted on account of the want of pre- 
valence in the ramifying ridges, and the changes to which they appeared liable?. 
Lamouroux’s Chrysaora seemed also to be objectionable from a want of suffi- 
cient agreement in the chalk fossil with the original description ; and although 
Spinopora may not have been established on an altogether satisfactory basis, the 
internal structure being unknown, yet when its ascertained characters were 
considered in the aggregate with or without ramifications, the polype which 
formed the coral was believed to have possessed an assemblage of structures 
sufficient to warrant the adoption of the genus. 
Respecting the position of Spinopora in a general classification, it may be stated, 
that M. De Blainville® associated the genus with others composed of corals for 
the greater part now admitted to have been formed by Ascidian Polypes ; and 
the same opinion appears to have been entertained by M. Milne-Edwards’, as he 
‘ Exploring Expedition, Zoophytes, p. 572. * Consult Goldfuss, tab. 11. f. 5, 7. 
’*Man. d’Actinol. p. 401. * Edit. 1836 of Lamarck, t. ii. p. 263-265. 
