THE PLANKTON OF THE FAEciE CHANNEL AND SUETLANDS. 371 



normality. The fifth feet are very peculiar, consisting each of one 

 branch only, each of the two basal joints and a terminal joint forming 

 three finger-like projections. The second and in greater degree the 

 third and fourth feet have their segments ornamented on the surface 

 with rows of fine spines, and the joints of the endopodites of the third 

 pair are fringed with spines. 



The absence of a secondary branch of the posterior antennse in this 

 species is remarkable. In other particulars, size and spinulation of the 

 feet segments, number of antenucT, joints, etc., it differs from any 

 known species of Pscudoajdopia. I have named it after Dr. Giesbrecht, 

 to whom I showed these drawings when recently I visited Naples. It 

 was captured in the surface tow-net off the island of Bressay, Shetland, 

 in March, 1900. 



EXPLANATION OF PLATES I.-IV., 



Illustrating Dr. E. N. Wolfenden's paper on " The Plankton of the 

 Faroe Channel and Shetlands." 



Plate I. 

 1. Aulographis furcdlata (nov. sp.}, a needle. 

 2 and 2a. Aulograpliis telrancista (?) (variety). 



2. A short-branched verticil. 



2a. A verticil with long branches. 



3. A needle of Aulacantha scolymnntha, 



4. 4a, ib. Aulodendron boreale {nov. sp.). 



5. Needles of Sp)hcerozouin {ovodimare'i). 



Plate II. 

 Challengerida. 



1. Challengcron ivalwini {nov. sp.). 



la. The peristome in different aspect. 



2. Challengcron halfouri (?) (variety). 



2a. The {leristonie (enlarged). 



3. Challengcron halfouri (?) (variety). 



3a. The peristome seen dorsally. 



4. Challengeria tritonis. 



5. Challengeria zetlandica {nov. sp. ). 



5a. VicAved ventrally. 



