SPIRIFERA. 25 



although almost circular when young (PI. IV, figs. 7, 9, 10, 11), it is in general more or 

 less transversely oval, or sub-rhomboid al, in the adult condition (PI. Ill, figs. 9 — 11 ; 

 PI. IV, fig. 6), the last having been considered by Professor Phillips to represent the 

 typical form of his species. The ribs differ also much, being either only here and there 

 duplicose, or, as is the case with many examples, having three or four ribs clustered 

 together, and thus producing a very remarkable appearance (PI. IV, fig. 6). The term 

 duplicicosta is not, however, very appropriate, since many species of Spirifera present that 

 peculiarity, which is also observable to a lesser degree in Sp. striata, to which Phillips's 

 form is very closely related. Professor M'Coy has likewise proposed to unite to the present 

 species the one named Sp. crassa by M. De Koninck =planicosta, M'Coy ; and although 

 the learned Irish author may perhaps be correct in his identification, I do not as yet feel 

 myself prepared to admit the point as an established fact. Sjp. crassa seems to con- 

 stitute a form intermediate in character between Sp. duplicicosta and Sp. Msulcata of 

 Sowerby, but I have not been able to examine a sufficient number of species to decide the 

 point to my own satisfaction. Professor M'Coy's illustrations of Sp. faciculata (PL IV, 

 fig. 11) so closely resemble many well-authenticated examples of the shell under descrip- 

 tion, that I have, with the sanction of both Professors Phillips and De Koninck, added it 

 to the synonyms of Sp. duplicicosta. Sp. fasciger, Keyserling, evidently belongs to the 

 same species, and has been so admitted by Professor M'Coy. 



Loc. Common in many Carboniferous localities, such as in the Great Scar Limestone 

 of Park Hill, Longnor, Derbyshire ; at Bolland and the Craven district ; at Lowick, in 

 Northumberland ; at Kendal ; and Poolvash, Isle of Man. In Scotland, Mr. J. Young and 

 Dr. Fleming possess it from Corieburn (Campsie), in Lanarkshire, as well as from West- 

 lothian. In Ireland, it is mentioned by Mr. Kelly as occurring at Lisnapaste, Malahide, 

 and Mullaghfin. 



Spirifera crassa, De Koninck. Plate VI, figs. 20 — 22 ; PI. VII, figs. 1, 2, 3. 



Spirifer crassus, Be Koninck. Animaux fossiles de la Belgique, p. 262, pi. xv bis, 



fig. 5, 1843. 

 Brachythyris planicosta, M'Coy. Synopsis of the Carb. Foss. of Ireland, p. 146, 



pi. xxi, fig. 5, 1844. 

 Spirifera crassa, TCOrbigny. Prodrome, vol. i, p. 149. 



— duplicicosta, M'Coy. British Palaeozoic Fossils, p. 415, 1855. 



Spec. Char. Transversely oval ; valves almost equally convex, and somewhat inflated ; 

 hinge-line shorter than the greatest width of the shell ; area triangular, of moderate width, 

 with cardinal angles rounded off. Beak small, incurved, not much produced. The mesial 

 fold is but slightly raised above the level of the lateral portions of the valve ; sinus wide, 

 not very deep. The valves are ornamented with from forty-five to seventy narrow, rounded, 



4 



