4H 



NEW YORK STATE MUSEUM 



10 mm; width at sicular extremity, .6 mm, increasing quite rapidly to maxi- 

 mum width of 2 mm. Sicular extremity furnished with rodlike virgella 

 (i.8 mm long), but without lateral spines. Lateral faces flat or slightly 

 concave, nearly smooth. Septal groove beginning at the sixth pair of 

 thecae on the obverse side and apparently absent on the opposite side. 

 Sicula long and slender (i.8 mm). Thecae numbering 12 in 10 mm in the 

 sicular part of the rhabdosome and 10 in the same space in the 

 mature part (25-30 to the inch), of the form of those of C. 

 typical is. Apertures and apertural excavations also as in the 

 latter species. Nemacaulus thin, rarely protruding and then but a 

 short distance. 



Locality and formation. Collected by Dr E. O. 

 Ulrich in the Sylvan shale of the Arbuckle mountains 

 in Indian Territory. 



Remarks. This species suggests at once its close 

 relationship to C. typical is by the long free parts 

 of the thecae and the short, narrow apertural excava- 

 tions, but it differs distinctly from that species in the 

 greater width of the earliest part of the rhabdosome, 

 the more gradual and more uniform widening of the 

 rhabdosome, its section and the less close arrangement 

 of the thecae (10-12 against 1-1-15 m IO mm); differ- 

 .ac'ograp- ences which warrant its separation as a distinct species. 



1 11 s miss issippien sis sp. • r 1 1 • • i i 



nov. Fig.366 Type specimen, Ihis iorm though not growing as wide as the 



preserved in demirehef. Fig. ° 00 



3 e 7 smaller rhabdosome. xe^ European C# l atus has the character of the thecae 

 and the rapid increase in width in the earlier stages in common with the 

 latter and may well be considered as a close relative or vicarious form of 

 the same. C. latus is found in the zone of Dicellograptus anceps and 

 is hence one of the last graptolites of the Lower Siluric. 



