DEAD SEA-LILIES. 77 



Palaeozoic crinoids mostly had the upper surface of 

 the calyx covered by a sort of dome, composed of 

 limy pieces of plates, the mouth and grooves not 

 being open to the surface. The grooves, in fact, 

 were veritable tunnels running to the mouth under- 

 neath the plates. These types are sometimes 

 referred to under the names Palasocrinoids and 

 Neocrinoids, but it would not be safe to regard these 

 terms, which were suggested by Dr. P. H. Carpenter, 

 as applying exclusively to geological age. 



There are considerable numbers of encrinites in 

 the Triassic formations. One of the most beautiful 

 of all is the Encrinus liliiformis, which is peculiar 

 to the Muschelkalk of Germany, a deposit not found 

 in the English Trias. Its flower-like head is sup- 

 ported gracefully on a rounded stalk, the joints of 

 which are curiously articulated with one another, 

 while the fringed arms are each composed of a 

 double series of tiny plates of lime. 



In the Jurassic deposits crinoids continue to be 

 common, more especially those belonging to the 

 genus Pentacrinus, the columns of which are five- 

 sided (pentagonal), having long slender arms. 

 Pentacrinus Briarem, so familiar to every visitor to 

 the Whitby Lias, possesses no less than a hundred 

 and fifty joints in the five pinnated arms of one 

 individual. These were covered with muscles and 

 an integument, which kept the innumerable ossicles 

 in their place, while the membrane was covered 

 with the minute cilia, the function of which was to 

 effect motion and propel the water down the grooves 

 that everywhere converged towards the mouth. 



