300 Report of the State Geologist. 



Family Zaphrentidjs. 



Streptelasma,, Hall, 1847. 



Streptelasma strictum, Hall, 1874. 



Streptelasma (Petraia) stricta, Hall, 1874. Twenty-sixth Rep. New York 



State Mus. Nat. Hist. , p. 142. 

 Streptelasma stricta, Hall, 1879. Thirty- second Rep. New York State Mus. 



Nat. Hist., p. 142. 

 Streptelasma strictum, Hall, 1883. Rep. State [.Geologist^ for 1882, expl. PI. I, 



figs. 1-10. 

 Streptelasma strictum. Hall, 1887. Pal. New York, vol. VI, p. 1. 



Horizon. — Shaly limestone. Indian Ladder, Catskill Creek, 

 Clarksville, Hudson, Schoharie and other localities in New York. 



The genus Streptelasma was proposed by Hall*" in the first 

 volume of the Palaeontology of New York. At the same time, 

 also, several species were described, but as no type was desig- 

 nated, 8. exjpansum., the first described, should be taken as such, 

 although the practice has been to employ S. coTniculum as the 

 typical form. The original description of the genus is as fol- 

 lows : '' Turbinate, gradually or abruptly expanding above ; form 

 ike Cyathophttlltjm ; terminal cup more or less deep ; lamellae 

 vertical or longitudinal, more or less spirally twisted together 

 when meeting in the center." 



As the type species {S. exjpansum) still remains uninvestigated, 

 and as the description above quoted is insufficient to distinguish 

 the genus from other Cyathophylloid corals. Sire telasma strictly 

 becomes little more than a name. 



Unfortunately, owing to the poor preservation of examples 

 from the Trenton limestone where the original specimens of 

 S. corniGulum were obtained, many investigators, among them 

 Edwards and Haime, ZiTTELandN^iCHCL80N,t have used for study 

 well-preserved specimens of the species from the Cincinnati group. 

 This species was described as Zaphrentis Canadensis. Much 

 confusion, therefore, has resulted. Edwards and Haime, regard- 

 ing S. corniculum as the type, say that Streptelasma is distin- 

 guished from Cyathophyllum "by the structure of the wall 



* Hall, 1843. Pal. New York, vol. I, p. 17. 



+ Both ZiTTEL (Handb. der Pal., Bd. 1, 2 Abth., p. 228) and Nicholson (Man. of Pal., vol. I, p. 297, 1889) 

 figure Z. Canadensis as S. corniculum. On the authority of Eominger (Geol. Surv. Michigan, Lower 

 Peninsula, vol. Ill, part II, p. 142. 1886) Edwards and Haime are Included. 



