CYBELE VERRUCOSA. 129 



pair of pits is the smallest and the basal tli3 largest. There is also a strong, broad 

 occipital furrow furnished likewise with a similar pair of deep lateral pits, situated 

 in the same longitudinal line as those on the glabella. The axial furrows are 

 shallow and wide, and do not diverge suddenly in front as they do in G. verrucosa, 

 but resemble in their course those of G. aspera, ending also similarly in a pair of 

 large, deep, terminal pits. The cheeks are somewhat wider than in G. verrucosa, 

 and the whole head-shield seems more transversely extended. The tubercles on 

 the glabella are large, prominent, few in number, and tend to be arranged in pairs 

 (as in C. aspera), and have some smaller tubercles interspersed. The anterior 

 border, which Linnarsson figures in G. aspera as armed with marginal spiniform 

 tubercles, is not preserved in our specimen. 



A complete description of this Girvan form is not possible owing to the 

 poorness of the available material, but it seems to me to bear more resemblance to 

 G. axpera than to G. verrucosa, though possibly it may be found to be specifically 

 distinct from both. 



Di 



iitensioiis. 



I 



II 



(From Ardniillan). 



(Prom Dow Hill, slightly compressed) 



9-0 mm. 



— 



7-0 „ 



6*50 mm. 



6-0 „ 



3-25 „ 



— 



5-25 „ 



— 



8-00 „ 



Length of head-shield 



„ of glabella 

 Width of ,, at base 



,, of ,, in front 



„ of cheeks at base . 

 Collections. — Mrs. Gray (I, II) ; Museum of Practical Geology (III). 

 Horizons and Localities. — Balclatchie Group (Llandeilo) : Ardniillan ; Dow Hill. 



4. Cybele verrucosa, Dalman ?. 



1822. ' Chaperon d'un Trilobite,' Brongniart, Hist. Nat. Crust. Foss., p. 145, pi. iv, fig. 11. 



1826. Calymene ? verrucosa, Dalmau, K. Sveusk. Vet. Akad. Haiidl., p. 285. 



1828. Calymene ? verrucosa, Dalman, Palaead., p. 76. 



1828. Calymene ? verrucosa, Dalman, Arsberiitt. Zool. Arbet., p. 134, note 1 . 



1829. Calymene ? verrucosa, Ferussac, Bull. Sci. Nat., vol. xix, p. 128. 



1845. Trilobites (Calymene) verrucosa, Lovcn, Ofv. K. Svensk. Vet. Akad. Forban'll', no. 3, p. 52, 



pi. i, figs. 5 a — c. 

 1845. Cybele verrucosa, Loven, loc. cit., no. 4, p. 111. 



Remarks. — The one head-shield of a Cybele from Craighead which may be 

 attributed to this species closely resembles Loven's figure and description, but the 

 larger tubercles on the glabella tend to range in four or five pairs down the centre. 

 The state of preservation renders the specific identification doubtful ; and the reason 



17 



