PHYLLOCARIDA— CLADOCERA— CALMAN. 157 



specimens would have to be classed under the former name. On the other hand, the 

 armature of the antennules is decidedly that of N. longicornis, and in view of their 

 place of origin they may, for the present, be referred to that species. It is evident, 

 however, not only from these facts but also from the observations of Thiele himself, 

 that the classification of the " forms " of Nehalia will have to be studied in greater 

 detail and with more abundant material before it is possible to say how many species 

 can be recognised or how far these can be subdivided into subspecies or varieties. 



CLADOCERA. 



I.— INTRODUCTION. 



The known species of Cladocera inhabiting the sea are few and their number is 

 not increased by the " Terra Nova " collections. A search through all the plankton- 

 gatherings has only resulted in the discovery of three species from five stations. One 

 of the species occurred both to the north of New Zealand and off Rio de Janeiro. No 

 Cladocera were obtained in Antarctic waters. 



II.— LIST OF STATIONS AT WHICH CLADOCERA WERE OBTAINED. 



Station 17. 26° 17' N., 20° 54' W. Plankton. 50-mesh net at 10 metres depth. June 30, 1910, 7.30 

 to 7.50 a.m. 

 „ 39 and 40. Six miles off mouth of Rio de Janeiro Harbour. Plankton. 50-meslinet at 2 metres 

 depth. Apr. 27, 1913, 11.0 p.m. to 1.30 a.m. and 2.30 to 5.0 a.m. 

 65. 23° 28' N., 34° 45' W. Plankton. 50-mesh net at surface. May 26, 1913, 1.30 to 2.0 a.m. 

 ,, 148. Bay of Islands, New Zealand. Plankton. 50-mesh net at li to 7 fathoms. Aug. 27-Sept. 15, 

 1912. 



III.— SYSTEMATIC NOTES. 



24. Penilia avirostris, Dana. 



Penilia avirostris, Dana, 1849, p. 47 ; id. 1852, p. 1269, pi. Ixxxix, figs. 2a-b ; Richard, 1894, 



p. 351, pi. XV, fig. 9. 

 P. orientalis, Dana, 1849, p. 47 ; id. 1852, p. 1270, pi. Ixxxix, figs. 3a-e ; Poppe, 1888, 



p. 295 ; Scott, 1894, p. 133 ; Richard, 1894, p. 350, pi. xv, fig. 12. 

 P. schmackeri, Richard, 1894, p. 344, pi. xv, figs. 5, 7, 11, 15, pi. xvi, fig. 8; Hansen, 1899, 



p. 4, p]. i, figs. 1-lb; Sudler, 1899, p. 109, 3 pis.; Richard, 1905, p. 9; Caiman, 1908, 



p. 232; Zernov, 1909, p. 500, 1 fig.; Brady, 1915, p. 136, pi. ix, fig. 1 ; Leder, 1915, 



p. 350, 4 figs. 

 P. pacijica, Kramer, 1895, p. 222, pi. xxiii, figs. 1-5. 

 P. sp. ?, Richard, 1894, p. 352. 



Occurrence. — Stations 39 and 40. Six miles off mouth of Rio de Janeiro Harbour. 

 Plankton at 2 metres depth. Many specimens. 



Station 148. Bay of Islands, New Zealand. Plankton at I5 to 7 metres depth. 

 Several separate hauls. Many specimens. 



Reviarks. — The specimens from the two widely separated localities mentioned 

 above agree equally well with the descriptions and figures of P. schmackeri given by 



