104 



KNOWLEDGE 



[May 2, 1898. 



pale tints as they reach the Arizona desert tract ; and a 

 practised naturalist can pick out with comparative ease 

 the specimens coming from this area from those of the 

 moister districts. 



It is not easy to obtain information as to the physical 

 features of the Arizona desert as compared with the 

 Sahara, and especially as to the amount of sand it con- 

 tains area for area ; but, judging from the comparatively 

 slight modifications which its mammals appear to have 

 undergone as compared with those of the more humid 

 regions adjacent, it seems not unlikely that these deserts 

 are of more modern origin than the Sahara and the Gobi. 



Whether or no it be true in this particular case, it may 

 be laid down as a general rule that the greater the amount 

 of sand to be found in a desert, and the greater the 

 difference between the animals inhabiting that desert from 

 those dwelling in the adjacent districts, the greater will be 

 the antiquity of the desert itself. In the case of a desert 

 forming a complete barrier across a continent, like the 

 Sahara, if the animals on one side are quite different from 

 those on the other, its antiquity will be conclusively 

 demonstrated. If, on the other hand, they are more alike, 

 the age of the desert will be proportionately less. 



THE KARKINOKOSM, OR WORLD OF 

 CRUSTACEA.-III. 



By the Eev. Thomas R. E. Stebbing, ji 



R.S., F.L.S. 



THE poet aays, " Tell me where is fancy bred." The 

 philosopher asks, " Where shall wisdom be found?" 

 To the carcinologist it is no less important to 

 inquire where he should search for Crustacea. To 

 him a comprehensive answer may be given that, 

 with one exception, there is no sort of place 

 on the garment of the globe where they may 

 not be encountered. Like adventures to the 

 adventurous, they will meet the expectant 

 observer as well in his daily rambles as in his 

 most audacious wanderings from Pole to Pole. 



Only in arid deserts the pursuit is at a 

 monstrous disadvantage. For almost every 

 crustacean specimen might claim a share in 

 the sweet singer's epitaph : " Here lies one 

 whose name is writ in water." Whether Mam- 

 malia have had marine ancestry may be dis- 

 puted by the disputatious, but few will care to 

 deny that crabfishes and the whole crustacean 

 tribe must have begun the business of life in 

 the sea. Out of water, and out of salt water, 

 the most part cannot sustain life at all. Almost 

 all of them are dependent for health and activity 

 on an abundant and constant supply of moisture. 

 The comparatively small number of terrestrial 

 species, by their close affinity to the aquatic 

 hordes, show that they themselves must have 

 had water-breathing progenitors. Some of them, 

 as is well known, make periodical pilgrimages to 

 lay their eggs in the ancestral sea. In lakes 

 which are evidently upraised and isolated frag- 

 ments of the ocean, crustaceans are found the 

 counterparts of others which are stUl marine. 



From the general facts of the distribution 

 one may beheve that the Crustacea began in 

 moderately shallow water, and that they have 

 thence spread themselves on the one hand to the shores, 

 up the rivers, over plains, valleys, and mountains, and 

 on the other hand into all depths and all quarters of the 

 widespread sea. Thus, to deal with them efficiently as 



a whole you need a dredge and a trawl, a boat and a 

 ship. You need a navy. That such an expression is 

 not hyperbolical can easily be proved. For though the 

 names of the Racehorsr, the DUcorery, the Vincennes, 

 the Samarang, the Astroluhe, and others may be little re- 

 membered in connection with the progress of carcinology, 

 yet the Luihtniwi, the Porcupine, and the Challenger, 

 the Talisman and the Traraillcur, the Blake and the Alba- 

 truss, have been made familiar to the present generation 

 by popular narratives as well as by volumes of profound 

 research. Without entering into rivalry with Homer in 

 his famous " Catalogue of the Ships," which is after all 

 only a sum in addition, one may make honourable mention 

 of the Novara, the Jos/pliine, the Vettor Pisani, the 

 Dijmphna, the Willem Barents, the Alert, the Hauch, the 

 Buccaneer, the HirondeUe, the Princesse Alice, the Hassler, 

 the Caudan, the Investigator, and stUl leave the list 

 uncompleted. Some of the vessels, no doubt, have been 

 less important for their size than for their services. A full 

 enumeration of them, nevertheless, would show a notable 

 international fleet. The immediate object of each expedi- 

 tion may have been geographical discovery, the sounding 

 of depths, the laying of cables, astronomical observations, 

 magnetic surveys, or other such trivialities ; but overruling 

 destiny employed them all — more or less — in catching 

 crustaceans. 



The ocean floor is difficult of access. The ocean surface 

 is more easily skimmed from a boat than from a man-of- 

 war. But, whether from boat or pier or ledge of rock, the 

 sweeping of that surface with a hand-net is productive of 

 treasure. It is rich in larval forms of various groups. It 

 is thronged with innumerable Entomostraca. For some 

 captures the night is the most favourable period. At some 

 times and places the abundance of individuals is over- 



yematocarcinus Agassizii (Faxon). Deep-sea Shrimp, taken b_y the Albatross. 

 Life size. Upper antenna imperfect. 



whelming. Square miles of ocean may be coloured by the 

 blood-red Calani known as " whale-food." To a cetacean, 

 with one or two thousand pounds worth of plates of whale- 

 bone depending from its cavernous skull, the extravagant 



