PHILLIPSIA. 45 



a pygidium figured which seems to have been intended for a caudal shield of this 

 very species ; but the author makes no allusion to the figure in his text, nor yet in 

 the explanation to the plate. 



Formation. — Carboniferous Limestone. 



Locality. — Derbyshire. 



This species most nearly resembles the pygidium of Ph. truncatula, Phil, sp., 

 but the acutely-ridged character of the axis in P. carinata suffices to distinguish it 

 from this and other species. 



Note on the Synonymy o/Phillipsia gemmulifera, Phillips, sp., 1836. (See ante, 



p. 17.) 



Although the Carboniferous Trilobites are but few in number, and are all 

 included in four genera, they have not escaped the usual trouble arising from 

 incorrect determinations. 



One of these occurred in reference to Phillipsia gemmulifera, Phillips, sp., 

 better known by the name of "Phillipsia pustulata," Schlotheim, sp., a name 

 applied to this form by Professor de Koninck in 1842-44 (see ' Descr. Anim. Foss. 

 Terr. Carbonif. de Belgique,' p. 603, tab. liii, fig. 5). 



This Trilobite, first known by a pygidiun only, was very carefully figured in 

 Brongniart's and Desmarest's ' Histoire Naturelle des Crust. Foss.,' 1822, pi. iv, 

 fig. 12, p. 145, where it is called " Asaphus" from the Black Limestone in the 

 environs of Dublin. 



It was next figured by Phillips in his ' Geology of Yorkshire,' 1836, vol. ii, 

 pi. xxii, fig. 11, p. 240, who named it Asaphus gemmuliferus. 



Buckland again repeated the figure later in the same year, and followed 

 Phillips' name of A. gemmuliferus. 



Professor de Koninck, in 1842-44, changed the name to Phillipsia pustulata, 

 quoting Schlotheim's ' Nachtrage zur Petrefactenkiinde ' (ii Abth., pp. 42-3, 

 Gotha, 1823, and ' Atlas,' p. 22, and plate xxii, fig. 6) as his authority. Now, as 

 Schlotheim's Trilobite differs very greatly from Phillips's figure, and also from 

 those given by Brongniart and by Buckland, and as, moreover, Schlotheim's 

 specimen was said to have been derived from the youngest Upper Transitional 

 Limestone (Devonian) of the Eifel, I felt great doubt in accepting Professor de 

 Koninck's correlation of Phillipsia gemmulifera with Trilobites pustulatus of 

 Schlotheim. 



These doubts I expressed in a previous part of this Monograph (see pp. 17 — 19, 



