JvLY 2, 1900.] 



KNOWLEDGE. 



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and though some are local withiu uaiTow limits, others 

 vie with the Anglo-Saxon race itself in range of travel. 

 Their own little legs, though fourteen in number, and 

 occasionally displaying great agility, could scarcely tarry 

 them verv far within the lifetime of an individual. Some 

 sj>ecies, which seem not only to attend but to precede the 

 footsteps of man in remote regions, have probably covered 

 the larger distances as an uninvoiced portion of the 

 meixhant's exports or the traveller's baggage, and then 

 by making short excur-sions from the point of arrival 

 have been enabled to assume the attitude of old in- 

 habitants. 



Nearest in general appearance to the terrestrial isopods 

 are the Sphjeromidre. which belong to a different tribe, 

 the Flabellifera, a highly important and interesting but 

 rather a miscellaneous group. In it the lu-opods or tail- 

 feet are lateral, forming with the telson a flabellum or 

 fan, whereas in other isopods (except the Valvifera) 

 they are terminal. The Sphieromidse till recently were 

 only known as marine. Now they have been obtained 

 from the fresh water of waiin springs and inland caverns, 

 the passage from salt water to fresh being, as one may 

 suppose, the intermediate step to a truly wonderful 

 change, from aquatic to subaerial existence. Human 

 beings who try making this change in the reverse order 

 usually find five minutes over long for the experiment. 

 But some of the laud isopods are far less sensitive, for I 

 have found a Porcellio immei-sed on the side of a lock 

 and making no attempt to leave the water, yet quite 

 lively when removed from it, and a recent experiment 

 has shown that a Porcellio scaher can remain under water 

 for four or five hours without material inconvenience. 



Cirolana borealis, LUljeborg. From U. J. Hansen. 



In the same tribe with the Sphseromids are the 

 Cymothoids, of which, if one were a literary fish, one 

 would write with a kind of hoiTor, on account of the 

 appalling diligence which these so-called fish-bears devote 

 to ichthyology. Not contented with persecuting ling 

 and haddock, cod and halibut, they assail with equal 

 feeirlessness dog-fish and shark and tunny. An extra- 

 ordinary feature in the life of some of the Cymothoids 

 is the virtual change of sex which is said to occur, 

 enabling the father of one family to become in turn the 

 mother of another, as though the ordinary marital 

 arrangements were not sufficient to perpetuate their 

 malicious brood. Those, like the JEgidte, which lead a 

 parasitic life, are furnished with shai-p hooked claws for 

 clinging, and with mouth-organs modified for piercing 



and tearing tlie skin of their hosts. In the ueai'ly allied 

 Cirolanidre the claws ai'e not powerfully uncinate, be- 

 cause these species ai'c more vagrant. Their jaws ai'e 

 adapted for biting rather than piercing. They are not 

 less enamoured of a fish diet than the ^gidre, and they 

 make their meals impartially of the living and the dead. 

 The celebrated Kroyer once found a large codfish riddled 

 by a swarm of Virohina boreal is. Ho hastily secured 

 some in his closed hand, b>it with equal ha.ste let them 

 go again, for they bit him barbarously and gnawed at 

 his naked flesh without remorse. Nothing could more 

 painfully show the unscnipulous character of these 

 creatures than that they should dare " to bite so good a 

 man," who was grabbing them purely in the interests of 

 science. 



Serolis hrumleyana, v. WiUenioes Suliui. Tlie feet omittcil. 

 from the "Challenger" Isoiioda. 



A passing notice must suffice for the flattened sand- 

 burrowing Serolidse, a family, so far as known, almost 

 confined to the southern hemisphere, but ranging from 

 shallow water down to a depth of two thousand fathoms. 

 A comparison of tiie species Serolis hromleyuna, 

 v. Willemoes Suhm, with the species Anthelura elonyata, 

 Norman, from the family Anthuridae, will show what 

 strange contrasts of shape are possible within a single 

 tribe of the Isopoda. In the Anthuridaj the great com- 

 paa-ative length and almost linear form of the trunk 

 may first appeal to the attention, but there is more to 

 engage it in the head and the tail, small as they both 

 are. The peculiar folding of one branch of each uropod 

 over the telson produces a certain resemblance to the 

 calyx of a flower. This suggested for the first formed 

 genus the poetical name Anthura, meaning flower-tail. 

 At the other extremity the head foi-ms a rather difficult 

 subject for study. At the first glance it might be sup- 

 posed to vary little in the different genera. But this 

 is not the case. The small closely compacted mouth- 

 organs show important distinctions. In some of the 

 genera they are evidently for perforation and suction, 

 but in others their mode of operation is not so clear, nor 



