12 



terminates in llie caudal spiue ; dorsal farrows moderately distinct upon 

 the anterior lialf of the pygidium, but become obsolete posteriorly; 

 lateral lobes slightly convex, indistinctly defined externally by the 

 broad, nearly Hat, marginal border ; their inner sides more clearly 

 defined, especially their anterior portions, by the dorsal farrows. 



Surface apparently smooth. Keniainder of the body unknown. 



The si>ecies differs, from ]\[. goniocercus Meek, in the less distinctly 

 triangular outline of the pygidium, its greater proportionate width, the 

 liroportioiKilly narrower axis, and the more distinct dorsal furrows. 



Fosifion and locality. — Eocks of the age of the Quebec group. Queen 

 Spring II ill, Schell Creek range, Nevada. 



Genus DicELLOCEPnALUs Owen. 



Dkjellocepiialus flagrioaudus {sp. nov.) — Pygidium contracted, 

 fan-shaped : lateral lobes each consisting of three seg'ments, directed 

 backward; the inner one of each side lying close to the dorsal suture, 

 nearly parallel with the axis of the body, or converging a little poste- 

 riorly, and becoming obsolete upon each side of a small but compara- 

 tively wide sloping border, that passes around the posterior end of the 

 axial lobe. The middle segments commence at the dorsal furrow of 

 each side respectively, near the anterior end of the pygidium, pass back- 

 ward parallel with the first, and project beyond the border as converging 

 posterior si)ines. The third and outer segments commence anteriorly 

 at the dorsal sutures, where they are very narrow, extend outward, 

 curve abrui)tly backward, parallel with the others, form raised lateral 

 margins of considerable but unequal width to the pygidium, and pro- 

 ject posteriorly as an outer pair of converging spines, similar to the 

 others. Axis ]nominent, especially at its apex, where it terminates in a 

 moderately shiirp angle, about one quarter wider anteriorly than pos- 

 teriorly, well defined by the nearly straight dorsal furrows, marked by 

 five or six distinctly-defined segments, which cross it almost transversely 

 but with a slightly sinuous course. 



The pygidium only of this species has been discovered, consequently 

 its generic relations are not accurately known, and it is referred only 

 provisionally to Bicellocephalus. 



Fosition and locality. — Strata of the age of the Quebec group, Schell- 

 bourne, Schell Creek range, Nevada. 



TRENTON PERIOD. 

 HYDROZOA. 



Genus Graptolithus Linmeus. 



Graptolitiius (DiPLOGRAPTUS) HYPNiFORMis {sp. uov.) — Stipcsim- 

 ple, slender; sides flat ; edges nearly straight and nearly parallel, the in- 

 crease in width being very slight from the proximal or basal end toward 

 the distal end. Serratares deep, narrow, sharply rounded or angular at 

 bottom, the inner and outer sides both rising at acute angles with the 

 axis of the stipe, those of adjacent cells joining together to form moder- 

 ately long, slender, mucronate points, directed strongly upward, between 

 the cells. At the proximal end of the stipe, small downward-diverg- 

 ing points are sometimes seen, like those of G. Whitjieldi Hall, and 

 other allied species ; and, like those species, this has a slender, thread- 

 like axis, passing longitudinally through the center of the stipe and 



