REPORT ON THE AMPHIPODA. 579 



peculiar. lu fact they very much agree with those of the thin and delicate Niiihargus 

 aquilex. Both species are to all appearance unwilling swimmers, struggling often in a more 

 or less upright position, then swimming back downwards, and soon sinking to the bottom, 

 Section 8, on nourishment, gives reasons for the opinion that the Amphipoda principally 

 if not exclusively feed on animal substances, whether dead or living. Section 9, on 

 commensalism and parasitism, distinguishes the species which have been noticed as 

 respectively inhabitants of Sponges, of Hydrozoa, of Echinoderms, of Tunicata, of Mollusca, 

 of Crustacea, of Fishes, of Eeptilia, of Cetacea ; those on Reptilia probably belonging rather 

 to the surface growth of sea-weeds than to the animals on which the sea-weed happens to 

 grow. Section 10 discusses the good and harm which the Amphipoda are supposed to do, 

 the good consisting in their constituting the food of various animals of more directly obvious 

 importance, the harm inculpating only two species, Ghelura terebrans, which bores into 

 submarine timber, and Gamrnarus locusta, which is supposed to destroy fishing-nets. 

 Section 11, on parasites, mentions as internal parasites Ecldnorrhynchus polijmorphuts, 

 Brems., Ecliincyrrhynchus proteus, Westr., Distomum sp., Gregarina longissima, Sieb., 

 Zygocystis puteana, Lachmann, Gregarijia elausi, Frenzel, CaUyntrochlamys phronimx, 

 Frenzel, Gregarina nicex, Frenzel, Gregarina capreUx, Frenzel, and as external parasites 

 " Epidylis Steini, Wrzesn., and Carchesium sp., on Gcmim.arus piilex ; Podophrya cydopum, 

 Clap., and Dendrocometes paradoxus. Stein, on Gamrnarus puteanus ; Vaginicola crystallina, 

 on Gamrnarus marinus ; VorticeJIa sp. on Darwinia compressa and on Lepidactylis arenaria ; 

 Carchesium. sp. and Podophrya crusiaceorum on Caprella xquilibra." 



Chapter V. is on classification, and begins by describing successively the systems of Mi In p.. 

 Edwards, Dana, Spence Bate (1857 and 1862), Lilljeborg, Boeck, Nebeski and (for the 

 Hypjerina) Claus, but without recognising the important service rendered by Axel Boeck 

 in laying stress upon the mouth-organs in addition to other important parts of the structure. 

 An interesting discussion follows bearing largely upon the Tanaidea, which it seems to be 

 a point of honour with Gerstaecker to include under the Amphipoda. The order Amphi- 

 poda itself, as distinguished from the Isopoda, he characterises " als annahernd homonom 

 segmentirte Malacostraca mit in der Eegel selbststiindigem, seltener (Laemodipoda, 

 Tanaidea) mit dem ersten Mittelleibsring verschmolzenem Kopftheil, zwei iibereinander 

 eingelenkten Fiihlerpaaren, nicht facettirtem Augen-Integument, im Mittelleib gelegenem 

 Herzschlauch und lediglich der Ortsbewegung (nicht der Athmung) dienenden Hinterleibs- 

 beinen.'' 



He makes three suborders, thus defined : — 



" Subordo I. Amphipoda genuina. Die sieben MitteUeibsringe frei, der erste nicht mit dem 

 Kopftheil verschmolzen. Hinterleib normal ausgebUdet, mit sieben (meist) selbststiindigen 

 Segmenten. Die Pedes sjiurii der drei hinteren Paare von donjenigen der drei vorderen 

 formell versohieden. Lamellose Kiemen iiach innen oder hinten von mehreren Mittelleibs- 

 beinpaaren. 



" Subordo II. Laemodipoda. Der erste Mittelleiksring mit dem Kopftheil zu einem Cephalo- 

 thorax verschmolzen. Hinterleib nebst den ihm entsjn-echenden GlieJmassen rudimentar, 

 auf einen stummelformigen Anhang des Mittelleibs reducirt. Dritter und vierter Mittel- 

 leibsring mit paarigen Kiemensacken, dagegen nur ausnahmsweise mit regular entwickelten 

 Beinen versehen. 



" Subordo III. Tanaidea. Der erste Mittelleibsring mit dem Kopftheil zu einem Cephalothorax 

 verschmolzen. Hinterleib normal ausgebildet. Die Pedes spurii der fiinf vorderen Paare 

 gleich gebildet. Keine Kiemen im Anschluss an die Mittelleibslieine. Die Seitentheile 

 des Cejihalothorax zu Athemhohlen umgebildet." 



A conspectus follows, which is not completed in this part, giving definitions of the divisions, 

 tribes, families and most of the genera which Gerstaecker accepts. Division I. Hyperina, is 



