122 ARTHUR E. SHIPLEY. 



Part IV. 



Geographical Distribution. 



The genus Phymosoma contains considerably naore species 

 than any other genus of the unarmed Gephyreans with the 

 exception of Phascolosoma. Including the new species 

 described by Sluiter, and by Selenka in his report upon the 

 Gephyrea collected by the "Challenger," the former genus com- 

 prises twenty-seven species, the latter twenty-five. Next to 

 these comes A spid OS iph on with seventeen, and Si pun cuius 

 with sixteen. 



Of the twenty-seven species of Phy mo so ma which have been 

 described, seventeen are found in the Malay Archipelago ; of 

 these seventeen, thirteen have been found there alone, whilst 

 four have a wider distribution. Three species are found in the 

 West Indies, of which two are found nowhere else ; five species 

 in the Red Sea, of which two are peculiar ; and four species in 

 the Mauritius, all of which occur elsewhere. 



It will thus be seen that the Malay Archipelago is the 

 headquarters of the genus, nearly two thirds of the number of 

 species composing the genus being found there, and nearly 

 one half of the whole number being confined to that region. 

 This is very possibly partly due to the fact that this region of the 

 world is much visited by collectors, and its shore fauna is pro- 

 bably better known than that of any other considerable area 

 within the tropics. On the other hand, the great predominance 

 of the species in these seas is undoubtedly striking. 



The following four species have a somewhat remarkable 

 distribution : 



(i) Ph. japonicum. — This extends along the Japanese 

 coast, and is again met with in the Fiji Islands and off the 

 coast of Australia. It was one of the two species brought 

 home by the "Challenger," and was found by that expedition at 

 Port Jackson. It thus has a considerable north and south dis- 

 tribution. On the other side of the Pacific we find another 

 species, — 



