CORALS FROM THE MOUNTAIN LIMESTONE. 191 



Derryloran, in Ireland. According to M. Keyserling, it is also met with in Petschora. 

 Specimens are in the collections of the Bristol, Cambridge, and Paris Museums, of 

 Professor Phillips of York, &c. 



The name of Lithostrotion was introduced almost a century ago by Luid (1760), 

 and applied to a fossil Coral, which must be either the above-described species, or a 

 species very nearly allied to it, and presenting the same generical characters. 



Luid's designation was more recently extended by Fleming to a generical division 

 characterised by that Zoologist, in the following terms, " Corals of aggregate prismatical 

 parallel tubes, with simple stellular discs," ('British Animals,' p. 508.) The genus 

 Lithostrotion, thus established in 1828, contained four species, the first of which was 

 Luid's original Lithostrotion, the species No. 4 (L. marginatum, Elem.), although too 

 imperfectly characterised to be determinable, evidently belongs to the same generical 

 division, but the species No. 3 (L. oblongum), differs from the two preceding ones, and 

 belongs to our genus Isastrea, and the species No. 2 (Z. floriforme), is referable to 

 neither of these forms, and must be placed in a distinct generical division. It is to this 

 last-mentioned genus, (designated recently by Professor M'Coy, under the name of 

 Lonsdaleia,) that Mr. Lonsdale applied the generical name of Lithostrotion, which, according 

 to the rules generally followed in zoological nomenclature, evidently belongs to the first, that 

 is to say to the group formed by Fleming with Luid's Lithostrotion and the allied 

 species. 



Goldfuss was not acquainted with any well-characterised Lithostrotion, and referred to 

 his genus Columnaria, (the typical form of which is C. alveola ta,) an almost undeter- 

 minable fossil, which he called C. lavis, 1 and which resembles Luid's Lithostrotion by its 

 generical features. M. Dana, in his elaborate work on Zoophytes, published in 1846, 

 very judiciously separates these last-mentioned corals from those which are in reality the 

 typical Columnaria of Goldfuss, and which he refers to a new genus, proposed by Mr. Hall, 

 under the name of Favistella; he was thus led to apply the name of Columnaria to Luid's 

 Lithostrotion and to the allied species, that is to say to the genus Lithostrotion of Fleming, 

 which must, however, remain distinct from the genus Columnaria, of Goldfuss, established 

 essentially for the well-characterised fossil described by the German Paleontologist under 

 the name of C. alveolata. 



Professor M'Coy had adopted the natural group designated by Fleming under the 

 name of Lithostrotion, and by M. Dana under that of Columnaria, but has given to it the 

 new name Nemaphyllum. 



In our opinion the limits of the natural group, so well represented by Luid's 

 Lithostrotion, ought not to be restricted to the corals which constitute compact masses, in 

 consequence of the complete lateral coalescence of the corallites, but should also comprise 

 those which, having the same structure and the same mode of multiplication, are not so 

 closely set and form fasciculate aggregations. Sometimes the two forms are met with not 



1 Petref. Germ., tab. xxiv, fig. 8. 



