REPORT ON THE AMPHIPODA. 1655 



science, together with some doubtful species that are reserved forfurther investigation, are 

 intended to form the subject of another small supplement to the list." Some valuable hints 

 on methods of collection are given in the introduction. Very useful notes are also inter- 

 spersed throughout the work in regard to the localities frequented by the different species, 

 and in many instances the colouring and movements of the living animals are described. 

 These observations which are evidently the fruit of long and careful study of the 

 Amphipoda give the work a far higher value than that of a mere catalogue. Of " Para- 

 themisto oblivia, Kroyer," taken in Sanda Bay, Mr. Robertson remarks, " only a single 

 specimen was obtained, and it is the only one that I remember of meeting with in the Firth 

 of Clyde. I had lately, from Dr. John Murray of the Challenger Expedition, some gatherings 

 taken by the tow-net in the Firth of Forth, where this species was in great abundance at the 

 surface, and at depths of 30 and 40 fathoms." (See Note on Brook and Calderwood, 

 p. 1640.) Mr. Robertson explains the value of tow-nets as used on board the steam yacht 

 " Medusa," " not only as surface-nets, but attached to the dredging-line at various depths, thus 

 giving a tolerably correct idea of the minute inhabitants of the various zones in the water, 

 to what extent they were distinct or intermixed, and whether those found at the surface by 

 night were met with in the under zones by day." 



1888. Rolleston, George, and Jackson, W. Hatchett. 



Forms of Animal Life, a manual of Comparative Anatomywith descriptions of 

 selected types. Oxford, m.dccc.lxxxviii. 



Pages 531-543 contain the account of the Crustacea. Claus' classification is followed. The 

 "Class Crustacea" is thus defined: — "Aquatic Arthropoda with cutaneous or branchiate 

 respiration : with two pairs of antennae, a limb-bearing thorax, either free or united more 

 or less to the head, and as a rule a segmented abdomen which may or may not carry limbs." 



Among many other remarks of value the following occur : — " The second antenna may become 

 uniramose, or the outer branch may be reduced to a scale or squame (many Thoracostraca). 

 It is minute in Apus and is lost in all Cirripedia and Hyperidx (Amphipoda)." But that 

 the second antenna is lost in all Hyperidae can by no means be admitted. 



" The primitive type of limb is probably that of the Gopepoda, which closely resembles the 

 Nauplius appendage. It has a basal stem carrying a more or less jointed or lamellate exo- 

 and endo-podite. Such a limb is seen in the thoracic appendages of Cirripedia and of the 

 Schizopoda among Malacostraca, and is generally found in the abdominal region." 



The class is divided into Entomostraca and Malacostraca, the latter thus defined : — " Head 

 composed of five, thorax of eight, and abdomen of six somites." 



The Malacostraca are divided into Leptostraca, Arthrostraca, and Thoracostraca, the definition 

 of the Arthrostraca being, " seven, rarely six free thoracic somites ; eyes sessile ; no 

 cephalothoracic shield." 



The Arthrostraca are subdivided into Amphipoda and Isopoda, the Amphipoda being defined as 

 follows : — " body laterally compressed ; branchiae on thoracic limbs ; first three pairs of 

 abdominal feet natatory: e.g. Caprelia, Cyanius, Talitrus, Orchestin, Gammarus, Hgperia, 

 Phronima." To the lateral compression of the body here mentioned there are several 

 exceptions. The characters given are generally applicable, but Caprella is little suited to 

 stand as the leading illustration, since in that genus the body is rather cylindrical than 

 compressed, the thoracic limbs are missing from the segments which carry the branchiae, 

 and there are no natatory abdominal feet. 



