498 



THE MICROSCOPE. 



invisible, pale yellow germ escapes from the egg ; this, if 

 placed under the microscope the first day after its birth, 

 has a very definite form, but not the least like a star-fish. 

 Four bands of long vibratile cilia guard the body at dif- 

 ferent points, and by their motion the little animal whirls 

 about in the water. 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. A dark mass 

 now collects within the trellised basket, and the rings are 

 united together by little bundles of rods, till they form 

 what looks like a joined pillar supporting the basket. 

 Gradually the plates enlarge and distort the outer wall ; 

 and 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, and the animal fixes itself upright 

 to a sea-weed or 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 extremity, and 

 the little creature looks when these valves are open much 

 like a microscopic wine-glass, and when closed like a 

 tulip bud." 



Echinidce} — Sea-urchins are found in abundance upon 

 our sea-shores, lurking among the rocks, where they entrap 

 their prey. Their spines and suckers are used as feet, or 

 as a mode of progression, even to the climbing of rocks, in 

 order to feed upon corallines and zoophytes : they march 

 along with ease where apparently no footing could be found, 

 or dig holes with their spines to bury themselves in the 

 sand, to escape pursuers, or hide from observation. The 



(1) Description of Plate 9 :— 



Asteroids. 



a, Astrophyton scutatum. 

 n, Ophiocoma rosula. 



N'CJDIBRANCHIATA GASTROPODA. 



b, Doris pinnatifida — back and 



side view. 



\C A LEPH.fi. 



c, Mquorea Forbesina. 



d, Medusce Bud. 



e, Thaumantias corynetes. 

 k, Cydippe pyletis. 



ECHINOIDRS. 



/, Echinus (A Young Sea-urchin). 

 g, Echinus sphcera. 



Tunicata. 

 i, Ascidice. 

 k, Botryllus violaceus, on a Fucus. 



Crustacea. 



I, Corystes cossivelaunus. 

 m, Eurynome aspera. 

 o, Pagurus Prideauxii. 

 p, Ebalia Pemnantii. 



