G. M. Thomson. — Natural Histori/ of Otai/o Harbour. 243 



66. Liljeborgia dubia Haswell. {Lilljeborgia haswelli Stebbing.) 



Common on the coast. Lives in pairs commensally with species of 

 hermit-crabs (Eupagiirus) in the upper whorls of the shells they inhabit. 



67. Leptamphopus novae-zealandiae G. M. Thomson. {Pherusa uovae- 



zealandiae G. M. Thomson.) 



Common in Otago Harbour. 



68. Eusirus antarcticus G. M. Thomson. {Eusirus lougipes Stebbing ; 



not Kroyer). 



Not uncommon in Otago Harbour. 



€9. Pontogeneia danai G. M. Thomson. 

 Common in rock-pools along the coast. 



70. Paramoera austrina Bate. [Megamoera fasciculata G. M. Thomson.) 

 Common in rock-pools along the coast. 



71. Melita inaequistylis Dana. (Melita tenuicoriris Dana.) 

 Common in rock-pools, and under stones between tide-marks. 



72. Elasmopus subcarinatus Haswell. 

 Frequently taken along the coast in the trawl-nets. 



73. Paradexamine pacifica G. M. Thomson. 



Very common along the coast. 



74. Paradexamine laevis G. M. Thomson. {Amphithonotus laevis G. M. 



Thomson.) 



Occasionally met with in Otago Harbour. 



No group of the Amphipoda has led to such divergence of opinion in regard 

 to classification as the Orchestidae, or, as Stebbing styles it in his splendid 

 monograph of the Gammaridea (in Das Tierreich), the Talitridae. This is 

 due in part to the fact that the sexes of the same species differ very con- 

 siderably, and that the males especially exhibit great structural changes in 

 the course of their growth and development. Stebbing divides the group 

 into thirteen genera, and in this he is followed by most carcinologists. With 

 all deference to such a body of authority, working, however, as most of them 

 do on material collected for them, I am inclined to dispute those distinctions 

 which are based on such slight and such plastic characters as the develop- 

 ment of the chelae of the gnathopods of the males. I have examined thou- 

 sands of specimens collected by myself, have dissected, compared, and 

 drawn hundreds of examples of New Zealand and Australian forms, and 

 have compared these w th European and Australian types received from 

 Messrs. Stebbing and Caiman and Professor Haswell. As a result of my 

 researches 1 am inclined to reduce Talitrus, Talitroides, Orchestoidea, Talor- 

 chestia, and Parorchestia to Orchestia, the first four being, based almost 

 exclusively on sexual characters, the last on the presence or absence of a 



