266 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.52. 



the specimens described by the original authors^ and doubtfully 

 included by them in tliis species has since been interpreted by the 

 present writer as belonging to an immature example of E. formosus. 

 In the latter species the denticles along the concave margin of the 

 posterior spine are closely approximated; in E. maccoyanus they are 

 widely spaced. The United States National Museum collection con- 

 tains well-preserved specimens of tliis form from the St. Louis lime- 

 stone of Mssouri (from the G. Hambach collection) . One of the most 

 perfect is catalogued as No. 8094, and shown in plate 7, figure 3. 



Genus STETHACANTHUS Newberry. 



The spines referred to tliis genus present some resemblance to 

 those of PJiysonemus, and also, in respect to their elongated inserted 

 portion, to certain species of Oracantlius, such as 0. vetustus, pre- 

 sently to be noticed. The maximum size in tliis genus appears to 

 have been reached in the species known as SteiJiacantlius productus, 

 from the Keokuk limestone of Iowa, the type and only known example 

 of which is preserved in the collection of the United States National 

 Museum. (Cat. No. 3841.) 



Two smaU-sized spines referable to tliis genus have recently been 

 described by L. Hussakof ^ from the Waverly of Kentucky imder the 

 new specific titles of S. liwmilis and S. exilis. They are preserved 

 in phosphatic nodules from one or two localities near Junction City, 

 in Boyle County. It is interesting to compare this occurrence of 

 Stetliacanflius spines with that of similarly formed spines under pre- 

 cisely the same conditions, witliin small, hard nodules, in the Caney 

 shale of Oklahoma, at the dividing hne between the Mississij^pian and 

 Pennsylvanian. A portion of such a spine, which camiot be specifi- 

 cally identified with certainty, is among the specimens obtained by 

 Doctor Girty from tliis horizon, and bears the Museum catalogue num- 

 ber 8110. It is from the locahty numbered 6079 in Doctor Girty's 

 Bulletin on the Caney Shale, published by the United States Geological 

 Survey in 1909. 



Genus HARPACANTHUS Traquair. 



This genus, known liitherto by but a single species, H. fimhriatus 

 (Stock), includes small, angularly bent spines, which are best inter- 

 preted as frontal claspers corresponding to those of recent male 

 Chimaeroids. 



HARPACANTHUS PROCUMBENS, new species. 



Plate 7, fig. 1. 

 Spines resembling those of H. fimhriatus but distinguished from 

 them by having a more closely spaced series of conical, recurved, 



> Pal. Illinois, vol. 6, pi. 22, fig. 3. 



s Hussakof, L. Descriptions of four new Palaeozoic Fishes from North America. Bull. Amer. Mas. Nat. 

 Hist., vol. 32, 1913, pp. 245-250. 



