Sea Lilies. 



ing the true zoological relation which the modern free Crinoids 

 bear to their fixed ancestors. At first a minute, almost invi- 

 sible, pale yellow germ escapes from the egg. This germ 

 swims, or rather rolls about, in the water, and gradually be- 

 comes larger, till under the microscope, about the end of the 

 first day after its birth, it has a very definite form, not the 

 least like a star-fish — more like a little glass shoe, with a 

 wider end, and a narrower end for the heel, and an oblong 

 hole to put in the foot. This hole is the creature's mouth. 

 Four bands of long vibratile cilia gird the body at different 

 points, and by their motion, hour after hour, the little animal 

 whirls about in the water, feeding, and leading a thoroughly 

 active life. About the end of the second day two rows, of 

 five each, of delicate calcareous trellised plates may be seen, 

 making a kind of five-sided basket within the wider end of 

 the shoe, and behind these a series of five or six open rings 

 run back in a line to the heel, where they seem to abut 

 against a larger plate. A dark mass now collects within the 

 trellised basket, and the rings are united together by little 

 bundles of limy rods, till they form what looks like a jointed 

 pillar supporting the basket. All this time the little gela- 

 tinous being, within whose body these changes are taking 

 place, swims about in the water and feeds, apparently utterly 

 unconscious of the growth of a guest within, which is steadily 

 compassing its destruction. Gradually, however, the plates 

 within the wider end enlarge and distort the outer wall. The 

 stem-like series of joints lengthen, stretching out the narrow 

 end with it. The old mouth disappears, the gelatinous wall 

 settles round the little living skeleton, a round sucker appears 

 in the original position of the " heel," and the animal fixes 

 itself upright to a sea- weed or to a stone at the bottom of the 

 tank. Five leaf-like valves, each supported by one of the 

 upper tier of plates, now open on the top of the wider ex- 

 tremity, and the little creature looks when these valves 

 are open much like a microscopic wine-glass, and when they 

 are closed, like a tulip bud. 



A little stalked Encrinite has thus been mapped out and 

 gradually developed within the gelatinous " pseud-embryo " 

 produced from the egg* of Cohatula. The five plates of the 

 lower row are the basalia, these afterwards become hidden. 

 The plates of the upper row correspond with the five trian- 

 gular plates round the mouth of Cenoceinus. These after- 

 wards disappear. The upper joint of the jointed column, 

 beneath which the stem is added to as it increases in length, 

 by the development of new joints, passes into the centro-dorsal 

 plate of Cohatula, and represents all the cirrhigerous stem- 

 joints of the stalked Crinoids; and the rest of the stem-joints 



