LONCHOCEPHALUS AND CREPICEPHALUS. 
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LONCHOCEPHALUS CHIPPEWAENSIS. (N. s.) 
(Tab. I. figs. 6, 14; Tab. L., a, fig 9.) 
Specific character.—This very minute species of Lonchocephalus rests chiefly on its small, semi-ellip- 
tical glabella, being little more than from one-tenth to three-tenths of an inch long ; ; in the short spicula, 
a spine projecting backward in the median line from the base of the glabella; in the horseshoe-shaped 
area surrounding the glabella, and forming the cephalic shield; in the semilunar shape of the caudal 
shield (seen at the base of fig. 6, Tab. I.), with a very narrow border deflected downwards; the axal 
lobe with four segments. 
This curious little Trilobite occurs by thousands in the soft gritstones of the Red Cedar or Menomonie 
branch of the Chippewa, occupying a position in F. 1 either of the third or fourth Trilobite-bed. Ina 
slab measuring three inches square, more than one hundred individuals can be counted, but in no instance, 
as yet, have the thoracic segments been discovered. 
LONCHOCEPHALUS HAMULUS. (N. 8.) 
(Tab. L., a, figs. 8 and 12.) 
Specific character.—All that has yet been brought to light of this species is the glabella, with its 
remarkable appendage, and a portion of the cheek-plate. 
The glabella is convex and undivided, quadrilateral in front, tapering behind, and provided with a 
long spine, attached to its base, and projecting, in the median line, in an arch backwards; this spine is 
much longer in proportion than that of the preceding species, and is formed in the shape of a fish-hook, 
as is well shown by a detached spine embedded in the medal-ruled slab, fig. 8; furrows of the glabella 
almost obsolete. The facial suture, as it proceeds with a slight sigmoid flexure around the eye-plate, is 
in close proximity to the glabella; then slightly diverging, it circumscribes a circular area in front of the 
glabella, proportionally greater than that of D. Minnesotensis. 
Caudal shield as yet unknown. 
This Trilobite occurs in the same light greenish-gray gritstones of F. 1 as the D. Minisczensis, up- 
wards of two hundred feet beneath the base of the Lower Magnesian Limestone, F. 2. 
CREPICEPHALUS. (N. G.) 
Generic character.—Some rich Trilobite slabs, occupying the position of the third Trilobite-bed at the 
Mountain Island section, contain numerous fragments of a Trilobite, a portion of the cephalic shield of 
which is seen on the medal-ruled slab, fig. 16 of Tab. I. A, on the left corner, as well as by figs. 10 and 
18 of the same plate. These, as far as preserved, approach somewhat in form to the genera Solenosema, 
Micropyge,and Endogramma ; but if the caudal shields, fig. 8 of Tab. I., and fig. 16 of Tab. I. a, corre- 
spond, which seems improbable, as they are abundantly disseminated in the same bed, and are mineralized 
in the same manner into a brown, ferruginous crust, contrasting strongly against the gray gritstone, then 
this Trilobite of Mountain Island, must constitute a genus distinct from either of these, and for which 
the name Crepicephalus is proposed. 
The rather flat, slipper-shaped glabella is tapering and slightly acuminated anteriorly, with a faint 
ridge in the median line; two small and very superficial depressions, and a posterior faint furrow, very 
partially divide the glabella. The facial sutures run nearly parallel to the margin of the glabella, and 
join a thickened, cord-like, anterior narrow border, enclosing a convex area, narrower in front than at the 
sides. Oblique plications can sometimes be traced on the cheek-plate, in advance of the eye, converging 
towards the apex of the glabella. 
If the associated pygidiums, fig. 8 of Tab. I., and fig. 16 of Tab. I. a, belong to Trilobites of this 
species, they are relatively larger than those of any of the above genera. The axal lobe has four seg- 
ments; side lobes bounded by a slightly concave ae which widens posteriorly, and of which the con- 
fines are almost rectangular, with rounded corn 
There are probably at least two species of rit genus; one about a third larger than the other. The 
