396 F, R. Cowper Reed—A New Species of Lichas. 
Il1.—Serpewick Musrum Notes. 
A New Spectres or LIcHAs. 
By F. R. Cowprr Resp, M.A., F.G.S. 
(PLATE XYII.) 
Licnas (HomoricHas) MELMERBIENSIS, sp. nov. 
T is rarely the case that we find complete individuals of any species 
of Lichas, especially in the Ordovician rocks, but several entire 
specimens belonging to a new British species have been recently 
collected by Mr. V. M. Turnbull from the Dufton Shales near 
Melmerby, and detached head-shields, pygidia, and hypostomes from 
the same locality and horizon are not uncommon. Since most species 
of Lichas have been founded on detached and isolated portions of the 
body, it is desirable to give a somewhat full description of this new 
form, which belongs to a group of the genus not previously recognised 
with certainty in the British Isles. 
Description.—Body oval, flattened, narrowing somewhat posteriorly, 
about two-thirds as wide as long. Head-shield broadly transverse 
and semilunate, measuring about 23 times as wide as long; lateral 
angles produced backwards and overlapping outer portions of the first 
4 or 5 thoracic pleure; median portion of head-shield projecting - 
abruptly, interrupting regularity of anterior curved outline at anterior 
lateral angles of glabella. 
Glabella, fixed cheeks, and inner portion of free cheeks form 
prominent swollen central mass, raised high above flattened outer 
portion of free cheeks, which are much produced backwards into 
large pointed genal angles and extend nearly to the middle of the 
thorax. 
Glabella somewhat oblong in shape, rather longer than wide, the 
axial furrows being subparallel with a slight outward concavity. 
The glabella is curved down more or less strongly in front of its 
middle, but is flattened from side to side. It consists of a median 
lobe with a long narrow neck, and is completely defined by the 
backward prolongation of the first lateral furrows to the occipital 
furrow, as in typical members of the section Homolichas. The median 
lobe has a frontal width equal to more than twice the width of the 
neck, and the triangular lateral angles completely extend in front of 
and overlap the anterior ends of the tricomposite lateral lobes. 
A slight widening of the neck of the median lobe takes place towards 
its base, owing to the divergence posteriorly of the prolonged first 
lateral furrows, but the median portion of the neck has nearly parallel 
sides. 
Tricomposite lateral lobes elongated - oval, somewhat pointed 
anteriorly, slightly curved outwards in front and less so at their 
base, towards which they narrow a little, but their axes are nearly 
parallel. Their base is rather abruptly truncated by the strong 
furrows which cut off the pair of rather large triangular or sub- 
rhomboidal occipital lobes, and are regarded as the displaced lateral 
portions of the occipital furrow. These occipital lobes are completely 
circumscribed, but are rather less swollen than the lateral lobes of the 
glabella. 
