GRIFFITHIDES. 27 



The following is Prof. Phillips' description of Asaphus quadrilimhus, taken from 

 the ' Geology of YorksTiire,' vol. ii, p. 239, pi. xxii, figs 1, 2. 



"Fig. 1. — The head. Margin quadrato-carinate, minutely striated; surface 

 smooth ; eyes very minutely reticulated. Fig. 2. — Abdomen." 



Prof. Phillips figures a portion of a detached head and an imperfect tail, but 

 they certainly did not belong to the same individual, and certainly not to the same 

 species. 



Formation. — Top of Lower Scar Limestones. 



Locality. — Bolland, Yorkshire. 



Genus 2. — Gripfithides, Portlock, 1843. 



Outline oblong-oval ; glabella pyriform, gibbous in front, destitute of lateral 

 furrows ; basal lobes inflated ; cervical lobe broad ; eyes small, lunate, smooth ; 

 axial furrow marking division of free cheek clearly defined, outline broadly 

 triangular, outer posterior angle sometimes produced into a cheek-spine. Thorax 

 with nine segments ; pygidium rounded, composed of about thirteen coalesced 

 somites. 



The subjoined is the original description of the genus GriffitJiides, given by 

 Portlock (1843), op. cit., p. 310. 



" Cephalothorax. — Semi-oval, longitudinal ; glabella strongly marked and gib- 

 bous, rounded in front, narrowed posteriorly into an obsolete neck, with a furrow 

 more or less distinct on each side ; cheeks, triangular spaces very slightly convex ; 

 wings either ending in an angle posteriorly or prolonged backwards in a flattened 

 spine. Eyes near the axis, not large, lunate, smooth (?). The minute neck 

 tubercle sometimes present. 



" Thorax. — The pleuripedes are compound, in number nine, or with the neck- 

 segment ten. 



" Pygidium. — Fully developed and strongly resembling that of Phillipsia. 



" A genus replacing Asaphs and Phacops in the Carboniferous system ; it is 

 dedicated to Mr. [afterwards Sir Richard] Griffith." Portlock also observes, p. 309 : 



" The determination of the true genus of the other Mountain-limestone Trilo- 

 bites to be now described is attended with considerable difficulty, as no fully expanded 

 specimen has as yet been found ' ; .... however, enough has been preserved to give 

 ... a general idea of the forms of the cephalothorax and pygidium, and of the struc- 

 ture of the thoracic segments. The form of the cephalothorax, and the position and 

 arrangement of the eyes, resemble closely the genus Asaphus as restricted, and parti- 



1 This was in 1843, but several complete specimens of Oriffithides have since been obtained. 



