12 P. T. CLEVE, NOTES ON SOME ATLANTIC PLANKTON-ORGANISMS. 



The range of distribution in the Atlantic is from Rio Janeiro to 56° N., chiefly in 

 the west. Temperature 24,5, mean of 26 obs., max. 28,4, min. 9,6. Salinity 35,39, niean 

 of 23 obs., max. 36, 40, min. 33,93. 



Theoconus junonis II kl. aff. 

 Plate IV Fig. 8. 



I have reproduced in Fig. 8 a drawing of the only specimen I have seen, as it is 

 of considerable interest for its occurrence W. of Norway. It is doubtless akin to T. jovis 

 or to T. junonis, but does not sufficiently agree with any. It was found in March 1898 

 at 62° N. 2° E. (temperature 7,4. Salinity 35, 12). The water was very poor in plankton, 

 as the tow-net catched in half an hour somc few plankton-specimens only, such as Cosci- 

 nodiscus oculus iridis and several radiolarians, not found at other spöts in the Atlantic. 

 T. junonis was taken by the Challenger Expedition from great depths east of Japan. Theo- 

 conus jovis has been found in the abysmal depths of the central Pacific. 



Length of the three joints 1 : 3,5 : 2, breadth 1:4:5. Cephalis 0,oie long, 0,02 

 broad. Thorax 0,05 long, 0,o« b road. Abdomen (incomj)lete) 0,03 long, 0,i millim. broad. 



Theocyrtis aculeata. N. Sp. 



Plate IV. Fig 11. 



Shell thick-walled. Length of the three joints 1:2:4; breadth 1:3:3. Cephalis 

 hemispherical, with a strong horn, longer than the cephalis. Thorax slightly inflated. 

 Abdomen cylindrical, with several rows of strong aculei towards the mouth. Pores of 

 the thorax and abdomen of nearly equal form and size, circular, regular, quincuncially 

 disposed, 3 to 4 times as broad as the bars. 



Length of the three joints: a 0,025, b 0,oe, c 0,n; breadth: a 0,03, b 0,076, c 0,09. 

 Horn 0,04 millim. long. 



Found in November 1898 between 56° N. 17° W. and 48° N. 29° W. Temperature 

 10,8 to 15. Salinity 35,27 to 35,44. 



Theocyrtis turris. N. Sp. 



Plate IV. Fig. 7. 



Length of the three joints 1:3:4, breadth 1:3:3. Pores of the thorax and ab- 

 domen of the same form and size. Cephalis small, hemispherical, with some scattered 

 pores and a horn of the same length. Thorax conical; abdomen cylindrical. Pores 

 roundcd, or rather subhexagonal, broader than the bars, quincuncially arranged. Length 

 and breadth of the cephalis 0,oi, of thorax 0,03. Abdomen 0,045 long, 0,05 millim. broad. 



Very rare at 45° N. 49° W. (January 1899). Temperature 12. Salinity 35,54. 



