512 PROCEEDINGS OF COLUMBUS MEETING. 



mentioned. With'the concurrence of Dr. Hilgard and Dr. Smith, I propose for it 

 the name of Middlelon formation. 



An article on the formation is in the hands of the editors of the American Geol- 

 ogist for publication. This will be followed by others. 



Mr. McGee also read the next paper for the author, who was absent: 



THE AGE \XI> ORIGIN OF THE LAFAYETTE FORMATION. 

 BY E. \V. HILGARD. 



The paper is printed in the American Journal of Science, 3d series, 

 volume xliii. 1892. pages 389-402. 



The following paper was read by title: 



pal.i:aster etch a u is, hall. 



BY A. II. COLE. 



The fossil which calls forth the following observations is an impression of the 

 oral surface of a starfish found in July last in the Hamilton shales in the quarry 

 belonging to ( Jolgate university at Hamilton. New York. 



The fossil has been compared with the type specimen from which Dr. Hall's 

 species was described and figured. As it agrees with the type in general, though 

 varying from the description in certain important characters, and by reason of its 

 perfect preservation reveals hitherto unknown details of structure, it seems best to 

 review the original description in so far as it relates to the oral surface. 



"PALjEASTER EUCHARIS (11. sA* 



■■ Body rather large : the largest individual being one inch and seven-eighths from the center of 



the body to tl xtremities of the rays; the whole having a robusi aspect; rays aeutely pointed at 



the extremity. 



"Ventral surface having deep ambulaeral grooves, bordered by two ranges of strongly tuber- 

 culose plates; the outer marginal range consisting of twenty-seven or twenty-eight plates, besides 

 a large, round, terminal or axillary plate ; the others are wider than long in the basal portion of 

 the ray, becoming gradually shorter toward the extremity, where they are rounded. 



"All the marginal plates are visible from the upper side, and usually appear as an additional 

 range of plates on each margin of the ray, making five with the three properly belonging to the 

 upper surface. 



•'The inner range bordering the ambulacra (adambulacral plates) are -mailer than the marginal 

 plates, about thirty-eight to forty in number; the basal or oral plate- are triangular, those of the 

 adjacent ray- uniting by their longer margin-, ami with a single minute plate situated at these 

 points. 



- The plate- of the exterior surface, both upper and lower, present a granulose or striato-grami- 

 lose surface, which appear- to have been produced by short setae or spines, and at the angle- of 

 the rays the marginal plate- are armed by a few spines, which are a- long or longer than the 

 transverse diameter of the plati s. 



"Ambulacra composed of a double range of short broad poral plates ossicula I, equal in number 

 to the adambulacral plate.-: their outer end- excavated on the posterior border, forming a com- 

 paratively large pore, |us( within its junction with the adambulacral plate. There appears to have 

 been but one range of pores in each set of ossicula, but these are large, distinct, and pas- between 

 the plates. 



*20th Ann. Rep. Y V. state < labinet of X.,t. Hist.. 18G7, p. 287, pi. ix. tigs. :;. :;■ . :;.< and I. 



