320 Transactions. 



legs somewhat densely covered with long hairs, tarsi long, slender, com- 

 pressed, densely haired. Last pair of legs somewhat shorter than the 

 preceding. Abdomen of male of 5 joints swbequal in length, 3rd rather 

 narrower than the 1st and 2nd, 4th nearly as wide as the 3rd, last broadly 

 rounded at the end ; margin fringed with very short hairs, some longer 

 ones being scattered on the surface. Abdomen of female with slight median 

 ridge along its whole length. 



Fulton and Grant have pointed out that the specimens from different 

 localities differ slightly as to the prominence of the obscure teeth on the 

 margin of the carapace, the hairiness of its surface, and the small teeth or 

 tubercles on the wrist and hand of the cheliped of the male. These features 

 were, however, found not to be constant, and I agree with them in con- 

 sidering all the forms as belonging to one species. Even if it should be 

 necessarv for systematic purposes to distinguish local varieties, it would not 

 affect the importance of the fact that the same fresh-water crab is found 

 in several lands now widely separated by sea. 



Art. XXXIV. - - The New Zealand Species of the Amphipodan Genus 



Elasmopus. 



By Charles Chilton, M.A., D.Sc, M.B., CM., LL.D., F.L.S.. Professor 

 of Biology, Canterbury College, New Zealand. 



[Read before the Philosophical Institute of Canterbury, 2nd December, 1914.] 



In "Das Tierreich " Amphipoda Gammaridea Mr. Stebbing describes nine 

 accepted species of the genus Elasmopus and four doubtful ones. Of these, 

 two are recorded as having been found in New Zealand seas — viz., E. sub- 

 carinatus (Haswell) and E. viridis (Haswell) — both of which were also known 

 from Australia, and were originally described in 1879 from Australian speci- 

 mens. In the case of the first species, which had been redescribed by Mr. 

 G. M. Thomson in 1882 under the name of Maera petriei, I pointed out many 

 years ago that there were two forms of male apparently both belonging to 

 this species, but no fuller investigation of the matter has yet been made, 

 although in the meantime the species has been recorded from the shores 

 of Ceylon and other places in the Indian Ocean. In the endeavour to work 

 out an Australian species of Elasmopus I have been led to look into the New 

 Zealand species, and the following notes are the result. 



The genus appears to be closely allied to Maera, and in some cases it 

 will probably be difficult to decide in which of the two genera a particular 

 species should be placed. The species E. subcarinatus and those allied 

 to it appear to be distinguishable from Maera by the small accessory 

 flagellum, the robust peraeopoda, and by the third uropod not reaching 

 far beyond the others. 



I have not included Maera viridis (Haswell), which Stebbing has placed 

 under Elasmopus, as it differs in several respects from the other species, 

 and appears to me to be very close to Maera inaequipes (A. Costa) and best 

 left under Maera. 



