316 PALAEONTOLOGY OF ILLINOIS. 



Of this curious type we only know the body below the summit of the second 

 radial pieces. In the structure of this part of the body, however, it differs 

 from the characters assigned to any known genus of Crinoids (excepting Cvp- 

 ressocrinus, from which it differs in other characters to be hereafter mentioned), 

 in having five basal pieces alternating with five subradials, which likewise alter- 

 nate with the radials, while all these pieces are so connected laterally as to form a 

 cup, without leaving any spaces for anal or interradial pieces. In several respects 

 it closely resembles Encrinus, but differs from the descriptions of that genus 

 given by all the authors we have been able to consult, in having a distinct series 

 of subradial pieces between the radial and basal pieces. It also differs from the 

 normal structure of that genus in having but two primary radials in each ray. In 

 a specimen of Encrinus, belonging to Smithson's private collection (since de- 

 stroyed by the fire at the Smithsonian Institution), examined by one of. us, in 

 the centre of the cavity occupied by the end of the column, five exceedingly 

 minute rudimentary pieces were visible by the aid of a magnifier within the range 

 generally regarded as the true basal pieces. If these were developed so as to 

 assume the character of true basals, then those usually regarded as such would 

 become subradial pieces, in which case our Crinoid would present no essential 

 difference, unless it may be in the other parts yet unknown. As Encrinus is, 

 however, always described as having the radial series resting directly upon the 

 basals, it is exceedingly improbable that the minute points mentioned above 

 were ever developed so as to become properly basal pieces. Hence we are un- 

 prepared to admit the existence of the genus Encrinus in our Carboniferous 

 rocks, and believe a new genus should be admitted for the form under consid- 

 eration. It is also highly probable that when we can compare the entire 

 structure of this Carboniferous type with that of Encrinus, it will be found to 

 present other important differences. 



A fine specimen of Cupressocrinus ahbreviatus of Goldfuss, from the Eifel, 

 now before us, shows that genus to agree exactly with Erisocrinus in the struc- 

 ture of the body up to the second primary radials, above which it differs 

 remarkably in having the rays each composed of a single series of pieces, and 

 soldered together all the way up; while in Erisocrinus each ray seems to bifur- 

 cate to form free arms on the second radials. Cupressocrinus also differs in 

 having a quadrangular central canal running the entire length of the column. 



Soon after publishing the description of this genus, we were led by its simi- 

 larit}' to a genus described by Prof, de Koninck, under the name PMlocrinus, 

 from the Carboniferous rocks of India, to believe it identical, and ranged our 

 species under that name. Later comparisons have caused us, however, to doubt 

 the correctness of this conclusion. If there is no mistake in regard to Philo- 

 crinus being without a range of subradial pieces, then the two types would be 

 clearly distinct. The fact, however, that the basal pieces in Erisocrinus are 



