192 U.S. NATIONAL MUSEUM BULLETIN 23 6 



into one of Lang's genera and that, as a result, he found the differ- 

 ences between his new species and those genera as big as those now 

 recognized to exist between Lang's many genera is not surprising if 

 the curious habitat, which must lead to structural differences, is 

 considered. That, on the other hand, the species should fit into 

 Nicholls' genus Mesamphiascus is not surprising at all if the very 

 wide limits of this impossible genus are borne in mind. I must also 

 contradict emphatically the choice by Nicholls that Amphiascus 

 parvus G. O. Sars, 1906, is the type of the genus Mesamphiascus 

 (see above). If this choice should be maintained, for which I see 

 no reason for it to be done, Mesamphiascus Nicholls, 1941, sensu 

 Humes, and Amphiascus G. O. Sars, 1905, sensu Lang, would become 

 subjective synonyms. The best solution undoubtedly would be to 

 erect a new genus for the reception of Mesamphiascus ampullifer 

 Humes, 1953 — which will find its place in the immediate vicinity of 

 Amphiascus G. O. Sars, 1905, sensu Lang, from which it is primarily 

 differentiated by the setation of the 3rd exopodal segment of leg 4, 

 having only 2 setae at the internal margin, while 3 occur in Amphiascus. 

 Nicholls' genus Amphiascoides has been defined properly by its 

 author (1941b, p. 81), and a distinct type, Dactylopus debilis Gies- 

 brecht, 1881, has been selected. Still, in Nicholls' sense, it is too 

 wide and would include species attributable to widely different genera, 

 as the following list clearly shows: 



debilis Amphiascella debilis (Giesbrecht, 1881) 



intermedius Paramphiascella intermedia (T. Scott, 1896) 



vararensts Paramphiascella vararensis (T. Scott, 1896) 



hyperboreus Paramphiascella hyperborea (T. Scott, 1903) 



neglectus Amphiascella neglecta (Norman and T. Scott, 1905) 



pygmaeus Haloschizopera pygmaea (Norman and T. Scott, 1905) 



hispidus (?) Paramphiascella hispida (Brady, 1880) 



nanus Amphiascella nana (G. O. Sars, 1906) 



nanoides Amphiascella nanoides (G. O. Sars, 1911) 



spinulosus Robertgurneya spinulosa (G. O. Sars, 1911) 



speciosus Amphiascella brevifurca (Czerniavski, 1868) 



dictydiophorus Robertgurneya dictydiophora (Monard, 1924) 



invaginatus Paramphiascella invaginata (Monard, 1926) 



sterilis Amphiascella sterilis (Monard, 1926) 



rostratus Robertgurneya rostrata (Gurney, 1927) 



commensalis Paramphiascella commensalis (Seiwell, 1928) 



ctenophorus Robertgurneya rostrata (Gurney, 1927) 



ilievecensis Robertgurneya ilievecensis (Monard, 1935a) 



roberti Paramphiascella roberti (Monard, 1935a) 



intermixtus Amphiascella subdebilis (Willey, 1935) 



aubdebilis Amphiascella subdebilis (Willey, 1935) 



ecaudatus Robertgurneya ecaudata (Monard, 1936) 



langi Paramphiascella langi (Monard, 1936) 



roberisoni Paramphiascella robertsoni (A. Scott, 1902) 



