1 !•<> 



mm, 



12-0 



55 



10-0 



55 



5-0 



35 



4-0 



,, 



4-0 



„ 



13-0 



„ 



5-0 



„ 



REMOPLEURIDES BICORNIS. 



Dim fusions (average example). — 



Length of head to base of frontal spines . 



glabella 

 Width of glabella between eyes 

 ,, ,, at base 



,, ,, in front of eyes 



Length of eyes 



„ genal spine 

 „ lower frontal spine . 

 Remarks. — This very remarkable and bizarre trilobite, though it may be referred 

 to the genus Remopleurides on the grounds of general resemblance in essential 

 features, must certainly be acknowledged to mark a distinct sub-genus, the 

 characters of which are those of this isolated species. The sub-generic name 

 Teratorhynchus is suggested for it in reference to the extraordinary development of 

 frontal spines. The specimen of a glabella from Ardniillan in Mrs. Gray's collection 

 which was figured by Nicholson and Etheridge (M., fasc. ii, 187 ( .>, p. 151, pi. xi, 

 fig. 16) as an example of R. barrandei is perhaps a young and immature individual 

 of R. bicornis ; for although the glabella seems to be evenly tuberculated and there 

 is no sign of the two anterior spines, yet it agrees with R. bicornis in the size and 

 shape of the eyes, the position of the two pairs of glabellar furrows in longitudinal 

 depressions, and the long rounded horizontally projecting tongue. I have seen 

 another similar specimen in Mrs. Gray's collection from the same locality. The 

 differences between this form and the typical R. barrandei as now limited are obvious. 

 Affinities. — This peculiar species is so distinct from all others of the genus 

 that a detailed comparison with any of them is superfluous. The long straight 

 anterior tongue to the glabella, horizontally extended ; the two frontal spines; the 

 two pairs of glabellar furrows in the longitudinal depressions on the glabella, the 

 position of the genal spines, and the peculiar pygidium are the chief distinguishing 

 characters. The relative width of the thoracic axis and pleural portions recalls 

 R. dorsospinifer, and the weakness of the pleural fulcrum is like R. obtusus, Salter. 1 

 The tuberculatum of the glabella reminds us of the British species //. platyceps, 

 M'Coy, 2 and R. tuberculatus, Reed. 3 



The curious curved frontal spine of Am/pyx hastatus, Ruede.,* is somewhat like 

 that of this species. The shape of the free cheeks and lateral origin of the genal 

 spines recall some species of Lichas. 

 Collection. — Mrs. Gray. 

 Horizon and Locality. — Balclatchie Group (Llandeilo) : Dow Hill. 



1 Salter, 'Mem. Gteol. Surv.,' dec, vii, pi. viii, p. '.». 



- M'Coy, ' Syuops. Silur. Foss. Ireland,' p. 44. 



3 Eeed, 'Quart, Journ. Geol. Soc.,' vol. k | L899), p. 7 is. 



' Ruedemann, ' Bull. 40, N.Y. State Mis.' ( L901 ). pi. in. figs. 1 In. 



