42 ME. T. SCOTT ON ENTOMOSTEACA 



Sabitat. Station 2, 25 fathoms tow-netting, January 1st (night collection). Lat. 

 3° 55' 3" N., long. 4° 7' 13" E., 50 fathoms tow-netting, January 20th (day collection). 

 Off Sao Thome Island (lat. 0° 34' N., long. 6° 31' 6" E.), 20 fathoms tow-netting, 

 Januaiy 23rd (day collection). Station 23, 235 fathoms tow-netting, Eehruary 5th (day 

 collection). 



Pleuromma ahdominale was obtained in 25 tow-nettings, eight of which were surface 

 gatherings, and seventeen under-surface, ranging in depth from 3 to 460 fathoms ; one 

 of the surface and seven of the under-surface gatherings were day collections, the others 

 were collected dm'ing the night, as shown in the formula : — 



1 day collection. 



r i day collection. 

 8 surface | 7 ^jgj^^ collections. 



Tow-nettings 25 •. ^ . t^ 



1 17 under-surface J ^ day ditto. 

 I 10 night ditto. 



In the adult males the abdomen was usually more or less distorted, as figured by 

 Prof. Brady in his Report on the ' Challenger ' Copepoda. 



The form agreeing with Pleuro^nma gracile, Claus, was obtained in a few of the tow- 

 nettings, and the difference between it and JPlenromma ahdominale. is so marked and 

 constant in the ' Buccaneer ' specimens that I have considered it preferable to record 

 them separately. 



Pleuromma geacilb, Claus. (PI. VI. figs. 11-14.) 



1863. Pleuromma gracile, Claus, loc. cit. p. 197, pi. v. figs. 7-11. 



1883. ? Pleuromma ahdominale, Brady (in part), op. cit. p. 46, pi. xii. figs. 1-16; pi. xsxi. figs. 13, 14. 



Habitat. Lat. 1° 55' 5" N., long. 5° 55' 5" E., 250 and 360 fathoms tow-nettings, 

 January 22nd (day collections). Lagoon, Sao Thome Island, surface. 



A form agreeing with the description and figures of Pleuromma gracile in ' Die frei- 

 lebenden Copepoden ' occurred in the gatherings described ; it seems to be distinct from 

 Pleuromma abdominals. 



Pleuromma princeps, n. sp. (PI. III. figs. 8-20.) 



Length (exclusive of tail-setae) 12 mm. Cephalothorax elongate, robust. Eorehead 

 acute ; postero-lateral angles of the last thoracic segment produced, shortly spiniform. 

 Left anterior antenna of male 25-jointed ; the right antenna is 22-jointed, hinged at the 

 eighteenth joint, the proportional lengths of the joints as in the annexed formula : — 



Lett. 50 . 20 . 20 . 15 . 20 . 20 . 20 . 15 . 20 . 25 . 3(1 . 30 . 40 . 45 . -50 . -SO . 50 . 50 . 55 . 38 . 8 5 . 37 . 40 • 30 . 10. 

 ~1~ 2 3 4 5 6 7 H 9 10 11 12 13 14 15 16 17 18 19 20 2l 22 23 24 25. 

 night. 7u . 20 . 20 . 20 . 20 . 25 . 1« . 15 . 12 . 12 . 25 . 24 . 30 . 45 . 40 . 50 . 60 . 13 . 70 . 80 . 30 . 7 . 



The nineteenth joint is furnished at the distal end with a tooth-like process which 

 extends over the base of the next joint. There are also, near the middle of the same 

 joint, one long and one very short spine, which extend in a forward direction along the 

 margin of the segment ; both antennae are sparingly setiferous. Posterior antennae as 



