FOSSILS OF THE DEVONIAN. 203 
Group. The latter is more slender, and has a less gibbous chamber of habi- 
tation. 
Formation and locality—Upper horizon of the Devonian limestone; The 
Gate, northwest of Eureka, Eureka District, Nevada. 
Genus CYRTOCERAS Goldfuss. 
Cyrtoceras Nevadense, n. sp. 
Plate xvii, figs. 7, 7a. 
This species is represented by a portion of the chambered tube 30™™ 
in length; the apical extremity, beyond a diameter of 10™", and the cham- 
ber of habitation having been broken away. 
Shell small, regularly curved, the depth of the arc of curvature being 
2m in a length of 30™. Transverse section subcircular, Apical angle of 
the lateral faces about 10°. Air-chambers numerous, varying in depth from 
2m to 3™" in a distance of 30", the larger extremity having a depth of 
17" and the apical section of 10". Septa smooth, with a concavity a little 
less than the depth of the air-chambers. Sutures horizontal, with a slight 
backward curvature on the dorsal side. Siphuncle central. Test thin. 
Surface marked by lines of growth that have a somewhat obtuse sinus 
on the ventral side. The internal mold preserves a trace of the exterior 
markings of the test. 
This species resembles Cyrtoceras (Gomphoceras) metula Hall (Pal. N. Y., 
vol. v, pt. 2, p. 360), of the Upper Helderberg Group of New York. It 
differs in the central position of the siphuncle, apical angle, and curvature 
of the sutures, — 
Formation and locality—Lower horizon of the Devonian limestone, 
Comb’s Peak, Eureka District, Nevada. 
Genus GONIATITES De Haan. 
Goniatites desideratus, n. sp. 
Plate xvii, fig. 10. 
Shell discoid; estimating from the depth of the umbilicus, the thick- 
ness of the disk is about 10". There were probably four volutions; two 
