186 



DEPARTMEM OF THE NATAL SERYICE 



curved hook; in the male these edges are rounded, and the fifth feet have a peculiar 

 vermiform process on the left side which distinguishes it from all others. It occurred 

 at Acadia station 44 in the vertical haul, males and females, some of the latter having 

 a spermatophore attached to the urosome or hind-body. 



C. tenuicornis was recorded at Acadia stations 17, 74, and 75; C. gracilis at 42, 

 44, and 75; C. minor at 44 (IS per cent at the surface), 56 (one male in closing net 

 from 210-140 fathoms), and 75 (males and females at the surface). C. minor is ano- 

 ther species not mentioned in " Nordisches Plankton " ; Wheeler observed numerous 

 females taken in Gulf Stream tow, July 25, 1899, the locality being 60 to 80 miles 

 south of Martha's Vineyard. 



4. Eucalanus and Rhincalanus.- — All the species of these two genera which are 

 included in " Nordisches Plankton " were encountered in stations tangential to the 

 Gulf Stream; many of the individuals were immature, especially was this the case 

 with Rhincalanus. When attempting to differentiate the young stages of RTi. cornu- 

 tus and nasutus, the conspicuous feature of the forwardly produced head with its ros- 

 tral filaments is not an unfailing guide. Figs. 2 and 3 show the appearance of the 

 fifth feet in young females of cornutus and nasutus; figs. 4 and 5 show the fifth feet 

 in young males of cornutus of two sizes. 



Fig. 2. — Rhincalmius ronaitua juv. $. Length 3 nun. 

 Fifth feet. Acadia station 44. 150-0 fathoms. 



Fig. ?. — Rhincalanus natiutu.^ juv. 9 3 mm. 

 Fifth feet, one shown. Same station. 



Fig 4. — Rhincalanvs cornutus juv, cf. 

 Fifth feet, hinder surface. 



Fig. 5. — Rhinra/anus cornutus juv. cf. Fifth 

 feet, front surface of older stage. 



