40 SILURIAN TRILOBITES. 



The tail, from very perfect specimens (figs. 19, 2.2, 23) is subtriangular, with roundel 

 sides and apex; pointed, highly convex; the sides regularly so, without any flattened 

 border. The axis is broad, and very gently convex; much more than half of the width 

 of the broad limb, regularly conical, and reaching four fifths the length of the tail. It is 

 annulated to the very tip by sixteen sharp rings. The sides are deeply grooved by 

 sixteen* nearly direct strong furrows, faintly interlined throughout, which gradually 

 radiate downwards, till from the tip of the axis they become longitudinal. Three or four 

 longitudinal ridges run from the tip to the end of the tail, thus completing the fan-like 

 arrangement. 



The incurved portion of the tail, seen in the small specimen (fig. 23), is narrow and 

 granulated, as the whole tail appears to have been. 



Locality. — Caradoc Sandstones of Shropshire ; plentiful in many places. (Cabinets of 

 Messrs. Liffhtbodv and H. W. Edo:ell : and in the Ludlow Museum, and Mus. P. Geology). 



P. (Ciiasmops) conophthalmus, Bocck ? PI. IV, figs. 24, 25, and PI. VII, fig. 25. 



Teilob. coxicophtiialmus, Bocck. Gsca Norvegica, i, 4, 1838. 

 Phacops — Emmrich. Dissert., 21, 1845. 



Calymene Odini, Eichwald. Sil. Syst. Eslhland. 



— — De Verneuil. Geol. Russia, t. xxvii, fig. S. 

 Phacops sclerops, Burmeister. Org. Trilob., ed. 2, tab. iv, fig. 5, 184G. 



— conophthalmus. Ibid., p. 91. 



— felixus, Salter (MS.). Ibid., Appendix of Species, p. 125. 



— CONOPHTHALMUS, Angelin. Palseont. Suecica, t. vii, figs. 5, G, 1852. 



— — Salter. Decades Geol. Survey, vii, Art. 1, p. / (exclude other 



synonyms tban those above), 1853. 

 Ciiasmops Odini, M'Cojj. Synopsis Woodw. Mus., t. i c, figs. 22, 23, 1851. 



P. {Ciiasmops) ova t us, capitc valde transverso, quam longo fere tcr latiorc, graniiloso 

 convexo [caudd brcvi, 8 — 9 cosfatd~\. Glabella convexa, antice valde dilatata, loLo 



froutali maosimo triangulato, oculum parvum imminente, lobis latcralibus supremis moguls 

 rotundato-irigonis, mediants obsolctis, bascdlbus linearibus, cervical/' lalo. Gena convexa 



fere gibbts, marginatee, angulis in cornua brevla ewtensis, oc/do brer I, lined fadali impressd. 

 Cai'da [associate/] lata, punctata, rlr margii/afa, a.vi conlco 9 — 10 annulato ; cost Is 

 latcralibus 8 arcuatls, duplicatis. 



The head of this species differs at a glance from the one above described, in being so 

 much more transverse, only half as long as it is broad, and rather semicircular than 

 semilunar. Though fig. 25 (copied from my own original figure in the 'Cambridge 

 Synopsis') is not quite perfect — it is only the internal cast — there is enough to show thnt 

 it agrees better with Angelin's 1\ conophthalmus than the other species; and the tail 



* Angelin's figure lias 19 axal, and 18 side ribs. 



