1897.] KEW YORK ACADEMY OF SCIENCES. 289 



This peculiar spine has heretofore been known only b}- Mr. 

 St. John's figure and description cited above. Unfortunately 

 the tj'pe specimen was so embedded in the rock as to expose 

 only the posterior face. An enlarged view is given in figure 9 c 

 of a portion of the anterior surfice which shows numerous 

 parallel costte surmounted by tubercles separated by intervals 

 of four or five times their diameter. This is the normal surface 

 of Oracanthus and yet it does not tell the whole story in regard 

 to this species. 



Recently I have received a specimen from the St. Louis lime- 

 stone of Alton, 111., collected by Mr. William McAdams, which 

 is almost the counterpart of that described by Mr. St. John, 

 except that it shows the anterior face from near the base to the 

 summit. The ornamentation of this surface exhibits some re- 

 markable characters ; below it is like that in the figure cited 

 above, but from the middle of the spine upward the longitudinal 

 costffi become almost obsolete and the surface is occupied by 

 rows of relatively large rounded button-like tubercles somewhat 

 scattered where they first appear, but closely approximated 

 above. A fragment of the upper part of the spine seen by itself 

 would never be referred to Oracanthus, but would be regarded 

 as a portion of a spine of Xystriacanthus, DrejMnacanthus or 

 Asteroptychius,a\\ of which have somewhat similar ornamentation. 



There is little doubt that these small, straight, nearly cylindri- 

 cal spines with this compound ornamentation will, when other 

 specimens shall be procured that will show the base — wanting in 

 the two now known — be assigned a separate genus. 



Oracanthus lineatls, n. sp. 

 PL XXII., fig. 5. 



Spine three and a-half inches in length, broadly conical in 

 form, originally transversely thick, now much compressed, 

 summit abruptly brought to an acute point, sides set with rela- 

 tively large, conical, obtuse, striated tubercles arranged in verti- 

 cal rows ; on the anterior margin these tubercles are higher and 

 in part acute, posterior margin formed by two smooth or striated 

 edges which originally bordered a pulp cavity that reached 

 nearly to the summit. One of the sides reaches back much 

 further from the anterior margin than the other and it is evident 

 the spine was never symmetrical, was not set on the dorsal line, 

 but was sunk obliquely into the integument somewhere on the 

 side like the modified scales, the spinous scutes of Gasterosteus, 

 Climatius, Diplacanthus, etc. 



Transactions N. Y. Acad. Sci., Vol. XVI., Sig. 19, July 20, 1897. 



