710 THE PALEONTOLOGY OF MINNESOTA. ; 
L[Gerasaphes ulrichana. 
broadest; allare simple, unfurrowed, and all disappear quite abruptly at the marginal 
border. The posterior portion of the pleurz is smooth, and the extremital area of the 
border is slightly bent upward. The entire surface of the shield is covered with 
anastomosing, racemose, elevated lines, which are very conspicuous on the larger 
specimen, and clearly apparent on the smaller. This ornamentis one of the generic 
characters of the group given by Angelin: “densissime striolatus.” This species is not 
widely different, so far it is known, from Asaphus huttoni Billings,* from the Quebec 
group of Table Head, Newfoundland, except in the length of the axis, which exceeds 
that of the latter species. It isan excellent representative of the strongly segmented 
type of Asaphus for which Angelin proposed the name Ptychopyge. 
Formation and locality.—One of the smaller specimens is from the lower blue beds of the Trenton 
limestone at Mineral Point, Wis. (Museum No. 8402), and the others from an equivalent or Birdseye 
horizon at Cannon Falls, Minn. The latter are from the collection of Mr. Scofield. 
GERASAPHES,+ n. subgen. 
(G7ERASAPHES ULRICHANA, 2. Sp. 
The form for which this name is introduced, though small, and even imperfectly 
known in certain respects, is one of no little interest in its relation to the ontogeny 
of the asaphids. The specimens of the single known species (named in compliment 
to its discoverer, Mr. E. 0. Ulrich) consist of two cranidia and two pygidia, lying on 
the surface of fragments of a calcareous shale, from the horizon of the Utica slate, 
at the mouth of the Licking river, Ohio. Of these four examples, three are on the 
same piece of rock. The following description embodies not only the distinguishing 
characters of the subgenus, but also those of the typical species. 
Fig. 14.—Cranidium of Gerasaphes ulrichana, x 4. 
Of the two cranidia, one has a length of 44 mm., the other of 24mm. The form 
of this part is distinctly asaphoid. The facial sutures take their origin on the 
posterior margin, making an acute angle with it, thence passing inward in a slightly 
convex curve to the palpebral lobes which are situated at about one-third the length 
of the cranidium from the posterior margin. These lobes are not large and the 
course of the sutures in front of them is that characteristic of Jsotelus, being a broad 
* Palwozoic Fossils, vol. i, p. 271. fig. 237, 1865. 
+ Geraios, old; asaphes, asaphus. 
