140 Annals of the Soidli African Museum. 



pod not so well marked, 5th not quite equal to 3rd plus 4th arid pro- 

 portionately stouter, with more robust spines. 



Length : 8-10 mm. 



Colour : In spirit, uniform pinkish. 



Locality: Beacon E. of East London N. E., distant 10 miles. 

 52 fathoms. 3 <$, 1 ovigerous ? ; Umhloti Eiver mouth NW. i W., 

 distant 15 miles (Natal). 100 fathoms. 1 (immature) <$ . s.s. " Pieter 

 Faure." 12/7/01 and 19/12/00. (S.A.M. Nos. A2750 and A2751.) 



Geogr. Distribution : Arctic Ocean, North Atlantic, Norway (Kroyer, 

 Sars, etc.) ; California, 46-57 fathoms (Pearse). Sars regards its 

 occurrence in the Mediterranean (Heller, Costa) as very doubtful. 



TRIODOS n. g. 



Head with postero-antennal corners distinct, though not prominent. 

 One pair of eyes. Side-plate 4 obliquely truncate below posterior 

 angle (as in Ampelisca). Pleon with tufts of setae as in Hoploops. 

 Maudibular palp with 3rd joint elongate. Peraeopods 3 and 4 with 

 2nd joint very wide, anterior margin evenly curved, 5th joint without 

 transverse rows of spines, 7th joint as in Ampelisca. Pei-aeopod 5 

 with 2nd joint distally expanded, the plumose setae extending round 

 posterior angle but not reaching junction with 3rd, 3rd not shorter 

 than 4th, 5th equal to 3rd and 4th together, 6th narrow, 7th spini- 

 form. Third uropod with rami foliaceous, extending beyond 1st and 

 2nd uropods. Telsou of moderate size, deeply cleft. 



This genus combines in a remarkable manner the characters of the 

 three hitherto recognised genera of Ampeliscidae, whence the name, 

 signifying a "meeting of three ways." 



TRIODOS INSIGNIS n. sp. 

 (Plate XXVI. Figs. 8-10.) 



Head projecting slightly over base of 1st antenna, 1 pair of very 

 small corueal lenses in upper angles of head. Side-plate 1 strongly 

 convex below, not concealing base of 2nd antenna, inferior margin of 

 side-plates 2-4 not very convex. Pleon somewhat compressed, seg- 

 ment 4 with a triangular keel on its posterior half bearing a tuft of 

 setae behind, segment 5 with a tall upstanding keel on its posterior 

 half also bearing a tuft of setae behind, postero-inferior angle of 3rd 

 segment rounded. 



Telson a little longer than broad, ovate, cleft nearly to base, apex 

 with 2 setae. 



