REPORT ON THE AMPHIPODA. 535 



are given, historical review ; special classification ; alphabetical table of the genera and 

 species. These are followed by " Geographische Verbreitung." Under "Anatomie und 

 Histologie," are given, general form of the body, segments, limbs ; integument ; glands ; 

 nervous system ; organs of sense ; muscles ; connective tissue ; organs of respiration ; 

 circulatory apparatus ; organs of nutrition ; sexual organs. Next come " Entwickelungs- 

 geschichte," " Biologie," " Phylogeiiie." under which the structure of the Cyamidje is 

 considered, and lastly " Literaturliste." The various topics are handled with great 

 thoroughness, and the opinions of earlier writers are minutely and carefully criticised. 

 Mayer thus defines the family CaprellidsB : — 



" Lsemodipoden mit sohmalen, auf dem Querschnitt annahernd kreisrundem Korper. Kopf 



und 1. Brustsegment zu einem Cophalothorax verschmolzen, 2.-7. Segment frei. 



Epimeren fehlen. Kiemen am 2., 3. und 4. oder nur am 3. und 4. Brustfnsspaare, 



schlauchformig. Abdomen aus hochstens 5, wenigstens 1 Segmente zusammengesetzt, mit 



hoohstens 3, wenigstens 2 stark riickgebildeten Beinpaaren. Vorderfiihler stots 1 linger als 



Hinterfuhler. Fiisse an Zahl verschieden ; die nioht riickgebildeten siebengliedrig, ohne 



Scheere, aber mit einschlagbarer Klaue." 



Up to the date of Mayer's treatise there had been established eight genera, for the arrangement of 



which various useful tables are given. Cercops, Proto and Caprellina agree in having 



branchiae on the second, third and fourth segments ; the rest have them only on the third 



and fourth. Proto and Caprellina have more than two joints to the flagellum of the lower 



antennae ; the rest have only two. CapreUa and Podalirms are without the mandibular 



palp, which is present in the rest. Proto stands alone in having seven pairs of complete 



limbs on the perseon ; Protella has five pairs complete and two pairs rudimentary ; 



Cercops, JEgina, ^ginella, Caprella, have only five pairs ; Caprellina and Podalirius have 



four pairs complete and one pair rudimentary. In Cercops the pleon has five segments, in 



Protella two, in the rest only one. In jEgiiia, the abdominal feet are jointed, in ^ginella 



not jointed. But of Cercops and ^ginella Mayer does not speak from his own observation. 



Within the genus Caprella, the species may be divided, as pointed out by Haller, into two 



groups, those in which the lower antennaj carry " Ruderborsten," and those in which they 



carry " Sinnesborsten." They may be otherwise divided into two groups, according as in 



the male the basal joint of the second gnathopod is very long or is short. 



To Cercops is assigned the single species " Ceraps Holholli, Kroyer." Proto, Leach, has the 



synonymy, Leptomera, Latreille; Naupredia, Latreille; Naupridia, Milne-Edwards; 



Proton, Desmarest. The species assigned to it are, ventricosa, 0. F. JNIiiller ; hrmineovittata, 



Haller; ^^ Novx-Hollandise," Has well; and "? Proto cornigera," Has well, for Capii-ella 



cornigera, Haswell. This last species has three pairs of branchiae arranged as in Proto, but 



the first three pairs of pera30pods have not been observed, only the muscles of the body 



going to them are so little developed, as to produce the impression that the limbs themselves 



may be rudimentary, in which case Mayer would place the species in a new genus, Hircella, 



a name adopted by Haswell in 1884, without further observation of the appendages in 



question. 



The genus Caprellina, Thomson, has the one species longicollis, Nicolet, with "Novje- 



Zealandiae," Thomson, and brevicollis, Nicolet, for synonyms. 

 Protella, Dana, has the species phasma, Montagu ; gracilis, Dana, with australis, HasweU, as a 

 possible synonym; ecliinata, Haswell, for Caprella ecMnata, HasweU; and "Haswelliana," 

 Mayer, n. s., in which the last two segments of the perseon are coalescent. Haswell, in 

 1885, says of his Protella australis that "it is a very well-marked species and quite 

 distinct from P. gracilis of Dana, to which Mayer is inclined to unite it, both in the form 

 of the head and of the gnathopoda. The gnathopoda are not unlike those of P. dentata 

 [1 C. dentata] but in other respects the two species are quite different." Mayer remarks 



