FRAGMENTS OF SCIENCE. 



717 



present views, however, we can hardly sup- 

 pose that organisms acquired hard parts at 

 a very early period of their existence, and 

 fauna after fauna may have occupied the 

 globe and disappeared, leaving no trace of 

 their having lived. In such case we are not 

 likely ever to obtain from fossils definite 

 knowledge of the character of the earliest 

 faunas ; and the biologist must not look to 

 the geologist for direct information concern- 

 ing the dawn of life upon the earth. The 

 importance of detailed work may be inferred 

 from a consideration of the great increase of 

 our knowledge of the Permo- Carboniferous 

 faunas as the result of recent labors in re- 

 mote regions. It is specially desirable that 

 the ancient faunas and floras of tropical 

 regions should be more fully made known, 

 as a study of these will probably throw con- 

 siderable light upon the influence of climate 

 on the geographical distribution of organisms 

 in past times. 



A Lobster's Motions. The adult lobster, 

 as appears from Dr. F. H. Herrick's study in 

 the Bulletin of the United States Fish Com- 

 mission, lives and feeds exclusively upon the 

 sea bottom, which it never leaves of its own 

 accord in any considerable degree. In trav- 

 eling over the bottom in search of its prey, 

 the lobster walks nimbly upon the tips of its 

 slender legs. The large claws are extended 

 in front of the head, a position which offers 

 the least resistance to the water, while the 

 two hinder pairs of walking legs, which end 

 in hard, spurlike joints, serve as picks to 

 steady the movements of the animal. In 

 thus getting about, it has the constant aid of 

 the delicate swimmerets, attached vertically 

 to the under surface of the " tail," each of 

 which consists of a short stalk and two very 

 flexible blades. By the movements of the 

 swimmerets the lobster is impelled slowly 

 forward without the aid of the walking legs. 

 The branches of the swimming feet are 

 garnished with long, chitinous seke or hairs, 

 to which the eggs of the female are attached. 

 When taken out of the water the lobster 

 can only crawl in its vain attempts to walk, 

 owing to the heavy body and claws, which 

 the slender walking legs are unable to sus- 

 tain. In exploring its feeding grounds, where 

 an enemy is likely to be encountered, the 

 legs which carrv the long claws ai'e extended 



forward in front of the head or carried some- 

 what obliquely, their tips resting on the 

 bottom, and the long, sensitive " feelers " 

 are waved constantly back and forth to give 

 warning of any foe or other objects which 

 the eye may fail to detect. These are ex- 

 clusively organs of touch. If the anticipated 

 enemy makes his appearance, or if the ani- 

 mal is surprised, as when it is suddenly 

 touched with the blade of an oar or cor- 

 nered, it will immediately strike an attitude 

 of defense. It now raises itself on the tips 

 of its walking legs, lifts its powerful claws 

 over the head after the manner of a boxer, 

 and strikes with one of its claws at the 

 offending object, trying to crush it or tear 

 it to pieces. By far the most powerful or- 

 gan of locomotion in the lobster is the tail, 

 by the flexion of which it can scull itself 

 through the water with astonishing rapidity. 

 The lobster, though less active and keen- 

 witted than the higher crabs, can not be 

 regarded as a sluggish animal in any sense. 

 In the water its movements are graceful ; it 

 is wary, resourceful, pugnacious, capable of 

 defending itself against enemies which are 

 often larger than itself, and, if the occasion 

 requires it, of running about with the great- 

 est agility and speed. When a lobster is 

 surprised it seems to disappear with a single 

 leap or bound, as a locust or grasshopper 

 might do. It never, however, rises more 

 than a few inches or at least a few feet 

 above the bottom, and it is evident that 

 swimming at the surface would be impos- 

 sible, on account of the great weight of the 

 body. 



Jack Rabbits. The jack rabbits, which 

 occur almost everywhere in the Great Plains 

 and desert regions of the United States, are 

 so called also "jackass hares " and "jacks," 

 " narrow-gauge mules," and " small mules " 

 from the resemblance of their large ears 

 to those of the jackass. They may be seen 

 abroad. Dr. T. S. Palmer says in his account 

 of them, at almost any hour of the day. 

 Living as they do on the open plain, where 

 they are compelled to rely for safety on 

 quickness of hearing and on speed, their 

 ears and hind legs are developed to an ex- 

 traordinary degree. This gives them a some- 

 what grotesque appearance, but in reality 

 few animals are more graceful than they as 



