THE YOUNG NATURALIST. 



253 



phibian rept les. These plants are found in 

 excellent pr> serration, some being of remark- 

 able beaut' . One species, Astcrophyllitcs 

 joliosus, rese- ibles, as its name implies, a star; 

 a number of leaves radiating from the ends 

 of the stalks Many of the existing genera of 

 insects occu- and the wings of butterflies are 

 sometimes fc and in the nodules of clay-iron- 

 stone. I wi 1 have more to say further on 

 about the fo nls of the Coal Measures. The 

 next formati >n, the Trias, yields plants, shells, 

 sea-lilies, cr. staceans, reptiles, and traces of 

 birds and ra . mmals. The sea-lilies were most 

 beautiful crc :tures, and are not yet extinct. 

 They are i ccasionally obtained from the 

 Carribbean J-ea, by dredging. Sir William 

 Brown's mi ;eum, of this city, possesses a 

 most beautiful form of Encrinite (Sea-Lily), 

 named Pent srinus (Cenocrinus) Captft-Medusa, 

 or " Medusa s Head Encrinite." The "head" 

 of this spec.es, supplied with a number of 

 beautifully leathered rays, is supported on a 

 jointed stem. Whorls of arms occur at 

 intervals along the stalk, each whorl being 

 attached to a segment wider than the rest. 

 When living the arms were of infinite service, 

 in clinging a )d supporting the Encrinite in a 

 perpendicul? r posture. Three other existing 

 examples art exhibited above the table case 

 containing tl 1 " Medusa's Head." 



In the L. . uc formation, two genera of 

 Cephalopoda occur, viz. : Ammonites, which are 

 closely alliec to the Nautilus, and Belemnites. 

 The Belemnites resembled the cuttle-fish of 

 the present cay. The harder portion of the 

 animal is the most frequently found fossilized, 

 is shaped like an elongated cone, and has 

 another srna ler chambered cone called the 

 ahragmocone, that fits into the wide end. 

 Remains of t ,vo reptiles, called the Iguanodon, 

 and Megalosa -rus have been found in Liassic 

 strata. Boti have been restored in a most 

 able manner :<y Mr. 3. Waterhouse Hawkins, 

 F.G. S., whose gigantic models are marvels of 

 such skill an' I labour as can only be found in 

 so accomplished a geologist. My descriptions 

 are made from two reduced casts from the 



original by Mr. Hawkins. 



The Iguanodon M as about twice the height 

 of an average-sized man when standing erect, 

 and three times his length or thereabouts. 

 The tail was very broad, and about equal to 

 three quarters the length of the animal's body. 

 The Megalosaurus was of similar proportions 

 to the above, but while the head of the 

 Iguanodon is short and blunt, that of Mega- 

 losaurus is prolonged like that of an alligator, 

 and supplied with long teeth. In addition to 

 this, the latter possessed a hump on the back, 

 which is wanting in the former. 



The lithographic stone of Solenhofen in 

 Bavaria, occurs in the Liassic formations. 

 Its fossils are well preserved as a rule, both 

 shrimps and dragon-flies being found m it, 

 the latter being represented by. JEs'chna 

 longialata, an insect very similar to the JE. 

 grandis of our own ponds. 



(To be continued. J 



BRITISH BUTTERFLIES. 



By J. E. Robson ; with figures from life by 

 S. L. Mosley. 

 (Assisted by Contributors to the Y. N.) 



GENUS III. COLIAS. 



" Colias, a surname of Venus, from the 

 promontory of Attica, at which she was wor- 

 shipped." — A. L. 



Nearly fifty species of this genus are known, 

 of which two inhabit Britain. The prevailing 

 color is yellow or orange, with a black border, 

 some species having a violet or purple gloss in 

 certain lights. Many of the species, perhaps 

 all, have a pale variety of the female. It is a 

 widely soread genus, occurring all over the 

 world except in India and Australia. Its 

 members are sometimes found in considerable 

 numbers 'lying in one direction as if passing 

 from one place to another. They have been 

 observed thus at great distances from land. 

 Mr. Charles Darwin names an instance worth 



