436 JIESSES. T. AND A. SCOTT — REVISION OF THE BRITISH COPEPODA 



dorsum tapers gradually to the extremity of the abdomen ; the anterior part of the 

 eephalothoracic segment curves gently and regularly to the apes of the comparatively 

 small rostrum. On the lower rounded angle of the eephalothoracic segment, and imme- 

 diately j)osterior to the base of the antennules, there is a small but distinct and bright- 

 red pigment-spot, as shown in the full-size di'awing of the animal (PI. 36. fig. 21). 

 Antennules small, moderately stout, 7-jointed ; the proportional lengths of the joints 

 are nearly as shown in the formula : — 



No. of the joints : 1.2.3.4.5.6.7_ 



rroiiortional lengths : 7 7 7 4 3 3 3 ^ 



Secondary branches of the antennae 3-jointed, and reaching to near the middle of the 

 last joint of the primary branches ; the middle joint is very small, while the end-joint is 

 equal to about one and a half times the length of the first joint (PI. 37. fig. 12). 



Mandibles armed at the apex with a stout irregularly trifid process and a strong 

 conical blunt-pointed tooth ; a small and moderately stout plumose marginal seta springs 

 from a little below the base of the conical tooth ; the basal joint of the mandibular palp 

 bears a single short subapical seta in addition to the two 1-jointed branches (PI. 37. 

 fig. 26). Anterior foot-jaws very small, but moderately stout; marginal processes small 

 and crowded near the end of the first joint; terminal claws slender, curved, their inner 

 margin ciliate on the distal half (PL 37. fig. 34). 



Posterior foot-jaws very small, but similar in structure to those of Ectinosoma Sarsi 

 (PI. 37. fig. 51). 



The first four pairs of swimming-feet are slender, the outer branches considerably 

 shorter than the inner ones ; marginal setae elongate, slender, and not plumose (PI. 38. 

 figs. 5 and 18). Eifth pair somewhat like those of Ectinosoma temilpes (to be described), 

 but the lobes of the secondary joints are separated from each other by a deep sinus ; 

 there is also a transverse row of cilia at the proximal end (PI. 38. fig. 42). 



Caudal stylets nearly twice as long as broad (PI. 38. fig. 45). Ovisac large. 



Habitat. Pirth of Porth, off Burntisland ; Barrow Channel, near Barrow-in-Furness. 



Memarks. This is not the Ectinosoma erythrops of Dr. Brady's ' Monograph of the 

 British Copepoda,' though it agrees wdth the descrij^tion of that species in so far as it 

 possesses a red pigment-spot near the lower anterior angle of the eephalothoracic 

 segment. Ectinosoma Normani distinctly differs from that species, as well as from the 

 others described in these pages, by the structure of the mouth-organs and of the fifth 

 pair of thoracic feet. The red pigment-spot, though very conspicuous Avhen freshly 

 preserved, disappears after being in spirit for a few days. 



Ectinosoma tenuipes, sp. n. (PI. 36. figs. 25, 32, 35 ; PL 37. figs. 9, 19, 30, 47 : 

 PL 38. figs. 12, 17, 36, 52.) 



Description. Length -6 mm. (-/,- of an inch). Seen from the side the thoracic 

 dorsum is very gently curved and tapers gradually to the moderately stout abdomen ; 

 rostrum prominent (PL 36. fig. 25). 



Antennules 7-jointed, rather longer and much less rolmst than those of Ectinosoma 



