COPEPODA. 245 



Scolecithrix danae (Lubbock). 

 Taken at 18 stations in the Indian Ocean and round Ceylon. 



Scolecithrix brady Giesbr. 

 Occurred once in the Mediterranean, and at G stations in the Indian Ocean, the 

 latter being an addition to its known range. 



Scolecithrix chelipes, Gjksbr. 

 Taken only at one station, in the Red Sea, its only known habitat. 



Scolecithrix auropecten, Oiesbr. 

 A rare species was found in the Red Sea, an addition to its known range in the 

 Mediterranean and Atlantic. 



Scolecithrix tenuipes, T. Scott. 

 Like the preceding species, this was found in the Red Sea, its only previously 

 known habitat being the Gulf of Guinea. 



Ridgewayia, n. gen. 



Body cyclopoid in form, G eephalothoracic segments well defined. Abdomen 4-jointed, 

 anterior antennte 25-jointed. Posterior antennae 2-branched, the outer branch 

 consisting of 2 joints, the inner branch of many joints and longer than the outer. 

 Monti i organs very similar to those of Calanus and Temora. 



Outer and inner branches of 1st to 4th natatory legs all 3-jointed. Outer branch 

 of 5th pair 3-jointed : inner branch 2-jointed. 



The male of the one species occupying this genus being unknown, it is not easy to 

 fix with certainty the exact systematic position. In the anterior and posterior 

 antenna?, as well as in the mouth organs of the female, it closely resembles the 

 ( 'alaninte. In the segmentation of the first 4 pairs of natatory legs it agrees with 

 Calanus, but not in the 5th pair. On the whole we think that the position of the 

 genus should be amongst the Calanida?. At the suggestion of Professor Herdman 

 we have named this genus in honour of Sir West Ridgewav. who was Governor oi 

 Ceylon when the pearl oyster investigation was carried on. 



Ridgewayia typica, n. sp. Plate I., figs. I to L3. 



Length, female 0'85 millim. ; male unknown. 



Cephalothorax G-jointed, the cephalic segment equal in length to the four following 

 combined. The 5th thoracic segment has a strong hook pointing downwards on its 

 ventral surface. Rostrum short, broad and pointed. Abdomen 4-jointed, the genital 

 segment very wide and ecpial in length to the following two united ; it bears a similar 

 hook to that of the last thoracic segment on its right side posteriorly. Furcal rami 

 about twice as long as broad, each bearing 4 long terminal setae. 



