NAUSITHOE. 33 



Ephyropsidae Claus. 



sens. em. Vanhoffen (:92). 



The only members of this family taken during the expedition belong to 

 the subfamily Nausithoinae and to the genus Nausithoe. 



Nausithoe Kolliker, 1853. 

 sens. em. Vanhoffen (: 02 a ) ; Maas (: 03, : 04 c ). 



Nausithoidae with round gonads ; the eight gonads separate and equally 

 spaced. 



The condition of the peripheral canal system of this genus has been the 

 subject of much confusion. Haeckel ('80) describes the " Lappentaschen " 

 as ending blindly in the marginal lappets, the rhopalar canals alone dividing 

 and sending branches into the lappets. Claus ('83), however, showed that 

 this was erroneous, and by his studies, as well as those of Vanhoffen 

 ('92, : 02 a ) and Maas (: 03), it has been conclusively shown that the system 

 as a whole follows essentially the same plan in Nausithoe that it does in the 

 Periphyllidae. Other structures which have been obscure are the pedalia 

 and ring furrow. But Vanhoffen ('92, : 02 a ) and Maas (: 03) have recently 

 shown that these, though hardly to be distinguished in immature specimens, 

 are progressively developed with age. 



The history of this genus is an interesting example of the series of 

 changes through which so many medusan genera and species have passed. 

 It was founded for certain specimens, not altogether mature, from the Medi- 

 terranean, named iV. punctata (Kolliker, '53). Larger specimens from the At- 

 lantic were set apart as a different species, N. marginata (Kolliker, '53). Others, 

 differing slightly in form and color, were described by Gegenbaur ('50) as 

 still another species, N. albida. Finally, when at last large mature in- 

 dividuals did come to light, they were made the basis of a new genus, 

 Nauphanta (Haeckel, '80). Under this new genus, four species, N. challi ngt ri, 

 JY. polaris, N. vettoris pisani, and N. albatrossi, have been described by Haeckel 

 ('80), Fewkes ('88 a ), Vanhoffen ('92), and Maas ('97) ; while still a third genus, 

 Ephyroidcs, was instituted by Fewkes ('86). Within more recent years, as 

 more and more specimens have been gathered from different localities by the 

 various deep-sea exploring expeditions, the different species were successively 

 reduced, and the three genera reunited, by Vanhoffen ('92, : 02 a ). Mean- 

 while a distinct geographic color race of the original N. punctata, not pre- 



