-til’ HULLETIN OF THE NATURAL HISTORY SOCIETY. 
wide area in front of the glabella. The glabella, so wide in front 
(one- seventh wider than at the posterior lobe), recalls that of Ctr atopy ge 
forficula, Sars., of a similar horizon in Sweden.* 
PaRABOLINELLA cf. LIMITIS, Bl'(Vg. 
The middle piece of the head-shield of a young individual which, 
by its form, agrees with the figures of this species, given by Professor 
P»negger,T was found in these beds. Only one example was met with. 
The size of the shield is 2|x 4 + mm. The interior of the shield 
shows three pairs of furrows, a strong ocular fillet, and a well-marked 
eyelobe. 
Triarthrus Belli, n. sp. PI. XYIII, fig. 8. 
Only the middle piece of the- head-shield is known ; this is sub- 
quadrate, with narrow cheeks and anterior margin. 
There are traces of a very narrow anterior marginal fold, and 
behind it a narrow convex anterior area of the cheeks. The glabella 
is quadrate, rounded in front, and bears three pairs of furrows, which 
are progressively less bent backward from the back to the front pair, 
though the two posterior pairs are already parallel ; the anterior pair 
are (juite faint, and more strongly arched than the others. The gla- 
bella is somewhat keeled along the axial line. The fixed cheek is long 
and quite narrow, and is separated from the front area by a shallow 
furrow ; at the eyelobe it is about one-third of the width of the gla- 
bella, and at the back about one-half. The eyelobe is long, narrow 
and obscure. The posterior marginal told is narrow but prominent. 
The occipital ring is bent forward at the ends, and has a tubercle on 
the axial line. 
Sculpture. — This species has a smooth test, but under a small lens 
shows a somewhat uneven surface. 
Size. — Only one example known ; in this the middle piece of the 
head is 6 mm. long and 10 mm. wide at the back. Scarce. 
This species is clearly distinct from T. Beckii Green by its nar- 
rower cheek and v/ider space between the sutures in front. It resembles 
more closely T. Angelini Linrs, but it differs from the type of that 
* Die Silurischen Etagen. 2 und 3, p. 14, tab. iii, fig. 3. 
Die Silur. Etag. 2 und 3, p. 102, tab. iii, figs. 2 and 4. 
