52 Stone Lilies of the Trenton Lunestoncr 



the authors state that " the two specimens of ilns crmoid, Peniacrimis caput 

 Mediisce, now in the Bristol Institution, were taken in the Caribbean sea, 

 off Barbadoes ; and Mr. Scutchbiu-y informs us that he has reason to be- 

 lieve they were taken by the fishermen at a depth of from fifty to eighty 

 fathoms, in clear water with a rocky bottom. I'he side arms, and probably 

 the rays, encircled the fishing lines and clung with such tenacity that en the 

 fishermen drawing up their lines the columns became fractured, so that the 

 upper portions of the animals were taken into the boats, and the lower parts 

 left attached to the rocky bed of the sea, thus in a great measure proving 

 that they were fixed by an indurated base of calcarous matter." ^' 



The structure of this existing species of the Crinoidea is of the most 

 simple radiated character. It has a five sided column — five plates in the 

 pelvis — five rays which are free nearly to their base, and three plates in each 

 of the Primaries. Thcv are all subdivided several times, and form numer- 

 ous feather-like arms. In all the formations, from the Lower Silurian up to 

 the most recent, we find Crinoids, with the same structure of the rays, and it 

 may therefore be regarded as the typical or model form. 



There are, however, many genera which exhibit this plan of organization 

 in a greatly modified condition. For instance, the genus Platycriuus has a 

 pelvis of only three pieces, and these are often anchylosed into one, and . 

 although it has five rays, yet they consist each of one very broad plate at 

 the base and resting upon it a very narrow one, from the sloping upper sides 

 of which spring the secondary rays. The genus Cyathocrinus has two series 

 of pelvic plates of five each, and with the rays similar to those of Platycri- 

 nus, but with the addition' of a large abdominal plate between two ' of the 

 rays on one side. In these and most other genera, no matter how widely 

 differing from the t}-pical form, the radial system can be traced more or less 

 distinctly. In this work, we propose to designate the different plates of the 

 rays by numbers, as follows. The bottom or basal plate of each ray, 1st 

 Kadial, the next above it 2ud Radial, and the next 3rd Eadial. The secondary 

 rays will be numbered in the same manner as 1st, 2nd, 3rd, and 4th Secon- 

 dary Radials. The abdominal plates between the rays we shall call Interra- 

 dials. This is in part the system of nomenclature adopted by Professor 

 McCoy, an eminent Irish Pateoutologist, in Professor Sedgewick's recent 

 splendid work, the British Pal,^ozoic Fossils. * 



It is a gi-eat improvement upon the original nomenclature of Miller, 

 Vfho was the first to prepare a work upon the Crinoidea. 



In the Paleontology of New York, vol, 1, five species of encrinite^s ai*e 

 <lescribed as having been discovered in the Trenton limestone within that 

 State, up to the date of the publication of the work, in 1847. In our col- 

 lection there are more than forty species, about thirty-five of which are from 



* Austin's Monograph on recent and fossil Crinoidea, page 111. 



* Where there are two series of plates below the rays, ai* in Cyothocrinus, . 

 J'rofcgsor McCoy calls those of the second series Pp.imaky Radials also. They 

 do not, however, appear to belona: to the rays. There is a new Crinoid fipiurcd in 

 Silliman's Journal of July last, which clearl}'- shews that this part of Professor 

 McCoy'i system is not capable of general apjilicatioii. 



