CHAPTER XXVIII CONCLUSION To complete the sketch of the Malacostraca, the sub-order of the Amphipoda remains to be described. These crustaceans may be defined in a very simple manner as Edriophthalma having branchial sacs or vesicles connected with some or all of the last six of the seven pairs of limbs normal to the peræon or trunk. Of all the divisions of the sub-order which have been proposed, that which arranges them in three tribes, the Gammaridea, Caprellidea, and Hyperidea, still seems the most satisfactory. Chapters describing these tribes for this volume had been already written, when it appeared that they overflowed the utmost space that could be allowed. As room for them could only be found by an unsatisfactory curtailment of the earlier portions of the work, I have preferred to leave over this last section of the Malacostraca, hoping to engage the reader's interest in it at no distant future. For the exclusion of a group so important as the Amphipoda, and one so obviously within the scope of the present pages, an apology is doubtless due, but little or none need be offered for the omission of much else which the student might desire to know, since the extent of the subject and the limits of the volume must make it clear that no other course was possible. It would take a volume by itself to analyse in an effective manner the long and valuable disquisitions which have been written on the circulation, the nervous system, the viscera, the tissues, the intimate structure of the various organs of the senses, the connection between fossil and recent forms, and the difficult questions of genealogy. On all these lines of research knowledge is continually extending. The time may be expected to come when, not from any one of them by itself, but from all combined, a final system of classification will be established. Apart from all these questions the simpler groundwork of the student's knowledge of recent Crustacea will still be incomplete unless the history be extended to those other orders mentioned at the outset, which comprise forms as varied, as strange, as numerous as those of the Malacostraca. On the literature of the subject not a little that is entertaining might be written. That literature was scanty and unfruitful in classical times. At the restoration of learning it began, amidst idle tales and inexact observations, to lay the solid foundations of science. In the present century it has attained an astonishing development, aided no doubt successively by the perfecting of the microscope, by the extension of marine research, and by an all-pervading desire to arrive at the truth about the origin of species. To illustrate the difference between what was known of the Crustacea at the beginning of the last century and what is known of them at the close of the present, one is tempted to contrast the half-dozen lines which suffice for the whole class in the first edition of Linnæus's 'Systema Natura' in 1735, with the four thousand quarto pages and more than six hundred plates employed by the Challenger Reports between 1880 and 1888 in the discussion and illustration of a host of crustacean species of which most were previously unknown. The System of Nature,' it is true, began in small compass, and was repeatedly expanded in successive editions, but even in the thirteenth, published in 1788, that part of it which may fairly be regarded as a manual of all the Crustacea with which science was at that period acquainted, is swollen only to the extent of fifty-three octavo pages. In 1825 the French writer, A. G. Desmarest, could still confine within the limits of a single volume an able and meritorious survey of the whole subject, but not long afterwards the masterly History of the Crustacea,' 6 by Henri Milne-Edwards, completed in 1840, though perhaps three times as valuable as Desmarest's, was also three times as large. Since that date no work of similar scope has been carried out with any success in smaller compass, nor is it likely now that such a feat could be accomplished. The Jinnee has escaped from the casket, and no magician can ever again reduce its gigantic expansion to occupy the narrow receptacle from which it issued. INDEX ABD ABDOMEN, alias postabdomen, Abdominalia, an order of Cirri- Acanthaspidia (new name) typh- Acanthephyra, range of, 243; 244 Acanthephyridæ, defined, 242 Acanthocope, acutispina, spini- Acanthocyclus Gayi, 71 Acanthoniscus (preoccupied) ty- Acanthopus (preoccupied) clavi- Acetes, 221; indicus, found in the Achæus Cranchii, 106 Acicle, antennal scale or exopod, ALT Adamsia palliata, the hermit-crab's Ega, 348; bicarinata, rosacea, Agathoa loliginea, 353 Alaotanais, priority of, considered, 'Albatross,' U.S.S, 28, 30 Alcirona, insularis, Krebsii, 346 Alcyonium butchered to make a 290 larval Squilla, Alitropus, foveolatus, typus, 317, Alloniscus, cornutus, mirabilis, perconvexus, 431 Alpheus, 230; affinis, avarus, coma- ALT barus. 209; suggested in Tana- Alternation of sex in Cymothoidæ, Amalopenæus elegans, 219 Amblyops, synonym of Amblyop- Amblyopsis, abbreviata, crozetii, 269 Amboina, present from king of, found, 14, 16, 17, 22, 23; sizes Anapagurus, 161, 165; chiroacan- thus, ferrugineus, Hyndmanni, Anarthrura, 325; simplex, linearis Anaspis, recently discovered genus Anceus, synonym of Gnathia, 300, Anchialus, 267; agilis, pusillus, Anchistia, migratoria, 248; scripta, 249 Ancinus depressus, 365 Anilocra, asilus, 352; gigantea, Annulus ventralis of Cambarus, Anomala, tribe of Brachyura, de- Anomura, position of, 8; apterura, ARI 52, 133; pterygura, 146; reason Antennæ, first, alias antennules, Anthelura, 331; abyssorum, 333 Anthuridæ defined, 330 Antilibinia Smithii, tenacity of, Anuropidæ, suggested new family, Anuropus, 342; branchiatus, 345 Apoda, order of Cirripedes, 11 Appendags, a single pair to a Apseudes, 320; grossimanus, Lat- Apseudidæ defined, 319 Apterura, meaning of, 133 talpa, Apus Newberryi, large Phyllopod, 31 Arachnida, the class, 3 276 Aratus Pisonii, breathing arrange- Archer, Surgeon-Major, on crabs Arctomysis (pre-occupied) 267; Arctopsis, its priority over Pisa Arcturidæ defined, 369 Arcturides cornutus, 373 Arcturus Baffini, 370; resemblance Arctus, 194; ursus, 195 Argeia, depauperata, pugettensis, Argis lar, 228 Aristeus antennatus, 219 Aristotle, Carcinus Heracleoticus |