500 



HISTORICAL GEOLOGY. 



Trilobites existed of the Cambrian genera Agnostus, Dicellocephalus, Pty- 

 choparia, Bathyurus (seven species or more), and Bathyurellus (Figs. 621-624), 

 and also of the genera IllcBnus, Asaphus, Ceraurus (Cheiriirus), Amphion, 

 Ampyx, which have here their first American species. 



An Ostracoid, or bivalve Crusta- 

 cean, is represented much enlarged 

 617. 620. in Yig. 616 (a profile view in 616 a), 



and several of natural size in the rock 

 616 h. 



617-620. 



in Fig. 



Characteristic Species. 



1. Spongiozoans. — Beceptaculites ele- 

 gantulus B. (Fig. 597) was a hollow sponge, 

 with the thickness to the inner tube about 

 lialf an inch ; tubes passed from the outer 

 to the inner surface, which opened inward. 

 The species from Little Metis (Figs. 599- 

 603) occur in beds that contain also the 

 Brachioi^od Linnarssonia pretiosa B. (Daw- 

 son, Trans. Boy. Soc. Canada, 1889). The 

 stem of Protospongia mononema (Fig. 600) 

 is of doubtful reality, according to Hinde. 



2. Hydrozoans. — The characteristic Cal- 

 ciferous forms, besides those figured, are Phyl- 

 lograptus Anna H. , Tetragraptus bryonoides 

 H., T. fruticosus H., Didymograptus exten- 

 sus H., all of the vicinity of Quebec. The 

 Cryptozoon proliferum H. (1884), from Green- 

 field, Saratoga County, N.Y., and C. Steeli, 

 Seely and Br. , another species from Vermont, 

 if really organic, perhaps belong here. 



3. Echinoderms.— Stenaster Hiixleyi B, 

 (Fig. 6101, having a breadth of 5 lines, is from 

 Point Eich, Newfoundland. 



4. Molluscoids. — Fig. 611, Orthis (Bil- 



lingsella) grandmva B. ; Lingula acuminata, 



Camarella calcifera B. ; C varians B. (also 



Cephalopods. — Figs. 617, 618, Orthocei-as primige- from Newfoundland) ; CUtamhonites. 



nium; 619, Kionoceras (Orth.) laqueatum ; 620. r !.«■ ,i i t ,,.7 . -r, 



^ . /ox TT • T'- ci-T C1Q «io 5- Mollusks. — a. Lamellihranchs. Eu- 



CjTtoceras (?) Vassannum. Figs. 617, 618, 619. 



Hall ; 620, "W. B. Dwight. chasma BlumenhacMi B., Newfoundland; 



Tellinomya Angela B. 



h. Gastropods. — Ophileta compacta S., a fine species from Canada, is H inches across ; 

 Pleurotomaria Calcifera B., from near Beauharnois, Canada ; P. gregaria B., St. Ann's, 

 island of Montreal, Canada, extremely abundant ; 3Iaclurea matutina H., from New York 

 and Canada; MurcMsonia Anna B. (a long turreted shell, approaching the M. bellicincta, 

 Fig. 675), St. Ann's, the Mingan Islands; Eccyliomphalus priscus Whitf., a large open- 

 coiled shell from Fort Cassin, Vt. 



c. Cephalopods. — Orthoceras Ozarkense Shum. is from the Magnesian limestone, Ozark 

 County, Mo.; Lituites (?) Farnsivorthi B., a species partly coiled, and nearly 5 inches in 

 its longer diameter, and L. imperator B., are from the upper part of the Calciferous sand- 



