178 



PALEOZOIC TIME. 



Fig. 274. 



Hyolites gregarius. 



festinata B., 1J m. E. of Swanton, Vt. ; also, at same locality, another Orthisina and 

 an Orthis, and at the Straits of Belle Isle, two different species of Orthis and another 

 Orthisina ; on the St. Croix, Orthis Pepina Hall. 



c. Lamellibranchs. — An undetermined one is reported from Troy. 



d. Pteropods. — Fig. 274, Hyolites (Theca) gregarius M. & H., 



ffrom the Big Horn Mountains, lat. 43° N., long. 107° W., where 

 they are ci-owded together in great numbers on the slabs. H. im- 

 par Ford and H. Americanus Ford occur near Troy. A species has 

 also been found at Keeseville, N. Y. 

 e. Gasteropods. — Imperfect specimens of a Pleurotomaria and 

 Ophileta compacta, in Canada, and the former also at Keeseville, 

 N. Y. ; a Gasteropod of the form of a Capulus, in Texas (B. F. Shu- 

 mard); Platyceras primordiale II., at Trempaleau, Wis. ; Euomphalus? vaticinus H., 

 Lagrange Mt., Minn. 



/. Cephalopods. — Two species of Orthoceras occur in the Potsdam of Canada, in 

 the top layers, with the Lingula antiqua (or acuminata). 



Articulates a. Worms. — Fig. 265, casts of worm-holes of Scolithus linearis 



H., common in New York, Canada, Pennsylvania, Tennessee, and occurring also at 

 the Straits of Belle Isle. The Fucoides? duplex H. (Foster & Whitney's Lake Superior 

 Report, pi. 23) probably belongs to another species of worm. Serpulites Murehisoni H. 

 occurs in Wisconsin. Salterella rugosa B., and S. pulchella B., slender conical shells, 

 one half inch, or so, long, from Straits of Belle Isle, are regarded by Billings as allied 

 to Serpulites among Worms, but by others as shells of Pteropods. The S. pulchella 

 occurs in the Winooski Limestone in Vermont. 



b. Crustaceans. — (1.) Phyllopods. — No Phyllopods have been found, although they 

 occur in the British Primordial. (2.) Ostracoids. — Leperditia Trojensis Ford, at Troy. 

 (3.) Trilobites. —Figs. 266, 267, Conocoryphe minuta Bradley, from Keeseville, N. Y., 

 and also from Wisconsin , 266, the head-shield or buckler, with the side-pieces wanting, 

 none having been found united to the head ; 267, the pygidium ; C Adamsii B., and 

 C. Vulcanus B., at Highgate, Vt., and the former in Newfoundland; C. (Atops) tri- 

 lineata Emmons, at Troy and Bald Mountain, N. Y. ; C. Teucer B., in Swanton, Vt. ; 

 C. Iowensis Shum. (Fig. 269), from near the mouth of Black River, Iowa. Fig. 268, 

 Dicellocephalus Minnesotensis D. D. Owen, a trilobite six inches long, from the upper 

 beds, Lake St. Croix, Minnesota. The name of this genus is from BUeW-q, a shovel, 

 and KefraXri, liead (whence the spelling above). The same region in Wisconsin affords 

 species of Agnostus, Agraulos, Ptychaspis, Chariocephalus, Aglaspis, and Jlkenurus, the 

 last two only in the upper beds. Species of Agnostus, Agraulos, Dicellocephalus, and 

 Conocoryphe, in Texas. Agraulos f Ouoeni M. & H. is from the Black Hills, Dakota, 

 and the Big Horn Mountains; also, Olenellus (Elliptocephalus) asijihoides Emmons, 

 Bald Mountain and Troy, N. Y., a very large species; Olenellus Thompsoni Hall, 

 Swanton, also Straits of Belle Isle and East arm of Bonne Bay, Newfoundland, and 

 Bradore and Forteau Bays, Labrador; 0. Vermontana, Swanton and Straits of Belle 

 Isle, and also Bradore and Forteau Bays, Labrador; Peltura holopyga Hall, Vermont 

 shales; Agnostus nobilis Ford, Troy, N. Y. ; Bathyurus senectus B., B. parvulus B., 

 Straits of Belle Isle; B. vetustus and B. perplexus B., from East arm of Bonne Bay, 

 Newfoundland. 



Fig. 259 represents a track, probably of a large trilobite, from near Perth, Canada, 

 described by Logan, who names it Climactichnit.es Wilsoni. Fig. 258, track, supposed 

 to be Crustacean, called Protichnites 7-notatus Owen. 



The following are the genera of Trilobites represented in American Primordial rocks ; 

 1. Those peculiar to the Primordial: Paradoxides, Olenellus, Aglaspis, Chariocephalus, 

 Illsenurus, Pemphigaspis, Triarthrella. 2. Those occurring also in the following or 

 Canadian period : Agnostus, Amphion, Agraulos, Bathyurus, Conocoryphe, Dicello- 

 cephalus, Menocephalus, Crepicephalus, Ptychaspis, Bathynotus (Billings). The genus 

 most abundant in species is Conocoryphe. Of all, only Bathyurus continues into the 

 Trenton period. Triarthrella is very near THarthrus of the Trenton. 



