158 "TERRA NOVA " EXPEDITION. 



Eichard and by Hansen. Since Rio de Janeiro Harbour is the type-locality for 

 P. avirostris, Dana, our specimens taken a few miles away practically fulfil tlie 

 condition laid down by Richard (1905, p. 10) for the identification of his species with 

 that of Dana, and there seems to be no need to wait for further specimens from the 

 Straits of Sunda before withdrawing P. orientalis, Dana, also as a synonym. 



The genus Penilia, therefore, appears to include only a single known species which 

 has been recorded from Beaufort (North Carolina), Vera Cruz (Gulf of Mexico), Rio de 

 Janeiro, Mediterranean off S.E. Spain, Trieste, the Black Sea, various localities in 

 the Gulf of Guinea as far south as Loanda, Durban, Straits of Sunda, Hong Kong, 

 Port Jackson, Auckland, and Bay of Islands. It seems to be strictly neritic or coastal 

 in habitat, and, as Leder has shown, it is tolerant of large changes in salinity. With 

 the exception of its occurrences at Trieste and in the Black Sea, and possibly also of 

 the New Zealand stations, its range to north and south is limited by the mean annual 

 surface isotherms of 18° C. 



25. Evadne tergestina, Claus. 



Evadne tergestina, Claus, 1877, p. 140, pi. v, figs. 15-16, etc. ; Hansen, 1899, p. 11 ; Juday, 



1907, p. 157, fig. ; Scott, 1912, p. 580. 

 E. aspinosa, Kramer, 1895, p. 222, pi. xxii, figs. 1-8. 

 1 E. gibsoni, Brady, 1914, p. 2, pi. i, figs. 1-5. 



Occurrence. — Station 39. Six miles oft' mouth of Rio de Janeiro Harbour, 

 plankton at 2 metres depth. One specimen. 



Remarks. — The solitary specimen appears to belong to this species, with which 

 it agrees in the numbers of setae on the exopodites of the legs. It presents, however, 

 a slight but distinct notch on the dorsal edge behind the cervical organ, as in Brady's 

 figure of E. gibsoni, a species which may prove to be identical with the present one. 

 E. tergestina is known from many localities in the Tropical and South Atlantic, as well 

 as from the Mediterranean, the Indian Ocean, Australia, New Zealand, and Southern 

 California (Hansen, 1899, and later references given above). 



26, Evadne spinifera, P. E. Miiller. 



Evadne spinifera, P. E. Miiller, 1868, p. 225, pi. vi, figs. 11-13 ; Claus, 1877, pi. vi, fig. 21 j 

 Hansen, 1899, p. 10 ; Lilljeborg, 1900, p. 647, pi. Ixxxvi, fig. 18, pi. ixxxvii, figs. 1-3] 

 Apstein, 1910, p. 43; Scott, 1912, p. 580. 



Occur rence.—iitation 17. 26° 17' N., 20° 54' W. Plankton, at 10 metres depth- 

 Many specimens. 



Station 65. 23° 28' N., 34° 45' W. Plankton, surface. Two specimens. 



Remarks. — According to Hansen, this widely-distributed species is especially 

 characteristic of and abundant in the central southern area of the North Atlantic. 

 Apstein states that its occurrence in the oceanic plankton is associated with the 

 presence of Sargasso weed. 



