10 p. T. CLEVE, NOTES ON SOjME ATLANTIC PLANKTON-OROANISMS. 



bases as broad as two meshes. By-spines bristle-shaped, arising from all nodal points of 

 the meshes, half as long as the main spines. 



Diameter of the shell 0,i6; length of the main spines U,o6 millim. Meshes 9 in 0,oi 

 millim. 



Very rare at 19 N. 60 W. (1898 November). Temperature 27,5. Salinity 35,22. 



Lainproraitra erosa. N. Sp. 



Plnte IV. Fin; 2 .3. 



Shell flat conical, with slight collar stricture. Length of the two joints 1:4; 

 their breadth 1 : 3. Cephalis hemispherical, with a horn of IV2 the length and with ir- 

 regular rounded pores of unequal size. Thorax with large rounded pores of unequal size. 

 Its margin with distant, frequently double teeth. 



Cephalis 0,02 long, 0,03 broaxl; thorax 0,oii long, 0,i6 millim. broad. 



Very rare at 45 N. 49 W. (January 1899). Temperature 12. Salinity 35,r,4. 



Psilomelissa lougispiua. N. Sp. 



Plate IV. Fig. 4. 



Shell smooth, with strong collar structure. Length of the two joints 4 : 3, breadth 

 1:1. Cephalis large ovate, with numerous scattered circular pores of unequal size, larger 

 and more crowded towards the collar stricture. Thorax short cylindrical, with scattered 

 circular poi-es. From the collar stricture there arise three divergent spines of equal 

 tliickness throughout their whole length, as long as the cephalis. 



Cephalis 0,04 long, (),03 broad; thorax 0,028 long, 0,o:i millim. broad. 



Western tropical Atlantic (1898 January at 32 N. 74 W.; May at 41 N. alMV.; 

 December at 18' N. 67" W. Temperature 19 to 26, s. Salinity 34, 8s to 36, 01. 



Quadrilonche crux. N. Sp. 



Plate IV. Fig. 1. 



Four equatorial spines with apophyses, the other neadle-sha])ed. Equatorial spines 

 with conical ends, gradually narrowed towards the centre, winged along their wliole length, 

 except at the conical end. 



Length of the cross 0,i6 millim. 



Western tropical Atlantic, sparingly from 26^ S. to 36 N. Temperature 25,4, mean 

 of 13 obs., max. 28, min. 21,7. Salinity 36,4o, mean of 8 obs., max. 37,43, min. 34,88. 



