316 Systematic Paleontology — Middle Devonian 



Spyeoceeas nuntium Hall 

 Plate XLI, Figs. 6-8 



Orthoceras nuntium Hall, 1861, Descriptions of New Species of Fossils, etc., 



p. 51. 

 Orthoceras nuntium Hall, 1862, Fifteenth Rep. N. Y. State Cab. Nat. Hist., 



p. 79, pi. viii, figs. 3, 4. 

 Orthoceras nuntium Hall, 1879, Pal. N. Y., vol. v, pt. ii, p. 299, pi. xliii, figs. 



4-10, 13, 14; pi. Ixxxii, figs. 14, 15. 

 Orthoceras nuntium Grabau, 1899, Bull. Buffalo Soc. Nat. Sci., vol. vi, p. 



290, fig. 225 on p. 289. 

 Orthoceras (Spyroceras) nuntium Clarke, 1903, N. Y. State Mas., Bull. 65, 



p. 633. 

 Spyroceras nuntium Grabau and Shimer, 1910, N. Am. Index Fossils, vol. ii, 



p. 64, fig. 1272. 



Description. — Shell straight, regularly and rapidly enlarging from the 

 apex; transverse section subcircular. Air-chambers regular, numerous, 

 having a depth of 2 mm. where the tube has a diameter of 10 mm., and 

 are of about the same frequency as the annulations. Septa smooth, with 

 a concavity equal to more than the depth of the adjacent air-chambers; 

 sutures straight and horizontal, essentially corresponding to the annula- 

 tions : siphuncle subcentral, moniliform. Test very thin, rarely pre- 

 served; tube ornamented with regular, numerous, horizontal annulations. 

 Surface marked by regular, fine, thread-like, longitudinal striae, which 

 are crossed by finer, less prominent lines of growth; the longitudinal 

 striae are usually continuous, but are occasionally interrupted by the 

 lines of growth, of which there are about twelve in the space of two mm. ; 

 on the internal mold the striae are usually impressed, but they appear 

 as if rounded and continuous, and do not present the sharp, threadlike 

 character as on the interior. A large fragment has a length of 140 mm., 

 and shows forty-two annulations; portions of smaller individuals show 

 from four to six annulations in the length of ten mm., varying with the 

 diameter of the tube. This species is distinguished from S. crotalum by 

 its more frequent and less prominent annulations, and by the somewhat 

 coarser longitudinal striae; while it differs from S. caelamen in not hav- 

 ing the longitudinal striae rounded and often interrupted by lamellose 

 lines of growth. 



