ART. 21 ORDOVICIAN TRILOBITES — ULEICH 17 



on the other the test is not preserved at the corresponding place. Probably 

 these impressions represent the glabellar furrows. Occipital furrow shallow, 

 rather broad, not reaching axial furrows, its middle part slightly arched for- 

 wards, its lateral parts backwards. Occipital ring broad in the middle (from 

 back to front), tapering towards the sides; convexity of anterior edge about 

 the same as of posterior part of glabella, postero-lateral portions more strongly 

 bent down and flattened, antero-lateral portions gently rounded ; different por- 

 tions separated by fine furrow, which disappears at base of median spine, 

 which latter isi broken off in this specimen. Glabella and occipital ring orna- 

 mented with sparse tubercles and net of very fine ridges, except at impressed 

 places on glabella, in the anterior pair of which are a few rounded pits irregu- 

 larly distributed. Doublure of occipital ring with fine transverse striae. 



Fixed cheeks gently bent down, rather narrow, widest just behind front ol 

 glabella, gradually decreasing in width posteriorly to posterior margin ; this 

 continues far outside part in front, is rather strongly bent down and obliquely 

 cut off by posterior branch of facial suture, which here takes a sharp turn 

 outwards. Anterior margin of cheek directed somewhat backwards ; antero- 

 lateral angle rounded, inner part of cheek rather flat in the middle, sloping 

 down toward the margin. Inner anterior portion with net of ridges coarser 

 than on glabella, a more strongly raised ridge along lateral and posterior 

 margins. Palpebral lobe set off by clearly marked furrow, extending round 

 anterior and lateral margins of inner part of cheek, flattened, slightly bent 

 down at antero-lateral angle, rather broad in front, gradually tapering poste- 

 riorly. Anteriorly it continues underneath overhanging anterior portion of 

 glabella along foremost part of dorsal furrow. Where this furrow meets pre- 

 glabellar furrow (which here is the same as the anterior border furrow of 

 cephalon, since there is no preglabellar field), the palpebral lobe bends steeply 

 downwards, forming together with lateral part of narrow, more swollen, and 

 strongly arched anterior border, the small anterior spines characteristic for 

 this genus. 



None of the American species is A'ery closely allied to this youngest, 

 apparently early Silurian, species. It suggests a cross between the 

 T. hipunctatus and T. fractus groups, the general shape of the glabella 

 and the obscure depressions on its lateral slopes reminding of the 

 former, whereas the slight anterior overhang of the glabella and the 

 abrupt downward direction of the median denticles are more in accord 

 with the latter. 



Occwrence. — Leptaena limestone, Boda, Dalarne, Sweden, Holo- 

 type in the Museum of tlie Geological Survey of Sweden. 



TELEPHUS HIBERNICUS Reed 



Plate 2, Figures 18, 19 



Teleplius hibernicvs Reed, 1909, Quart. Journ. Geol. Soe. London, vol. 65, 

 p. 149, pi. 6, figs. 10 and 11. 

 Original description. — 



Several small detached head-shields of a trilobite, with the peculiar char- 

 acters of Telephus, occur in the crystalline reddish limestone (58) exposed west 

 of Gortbunacullin Farm bridge. None are very well preserved ; but, by piecing 



64441—29 2 



