BELONGING TO THE GEXERA BKAUYA AND ECTINOSOMA. 437 



Sarsi, sjiaringly setiferous ; a long slender sensoiy filament springs from the third j oiut, 

 the ujiper distal angle of wliich is produced to form the base of the filament (PL 36. 

 fig. 35j. The annexed formula exhibits the proportional lengths of the joints very 

 nearly : — 



No. of the joints : 1.2.3.4.5.6.7 



Proportional lengths : 8^"~9 5^8 4 4* 



Antennas slender ; secondary branches S-jointed, very slender, scarcely longer than 

 the second joint of the jirimary branches ; the first joint is rather shorter than the last, 

 while the middle ono is small (PI. 37. fig. 9). 

 . Labium with a very slender " hook " (PI. 36. fig. 32). 



Mandibles armed on one side of the apex with a broad tridentate process and on the 

 other side with a moderately stout spine, w^hile between these is a large conical tooth ; 

 the branches of the palp are slender (PI. 37. fig. 19). Anterior foot-jaws somewhat 

 like those of Ecti)iosoma Sarsi, but scarcely so stout (PL 37. tig. 30). 



Posterior foot-jaws very slender, and the end-joint is nearly equal to half the length of 

 the one immediately jireceding (PL 37. fig. 47). 



The first four pairs of swimming-feet have the inner branches moderately stout and 

 elongate, but the outer branches are considerably shorter than the inner one and very 

 slender (PL 38. figs. 12 and 17). 



Pifth j)air small ; the produced inner portion, of the basal joint is furnished with a 

 short stout spine and a long spiniform seta ; the secondary joint is nearly as broad as 

 long and does not reach much beyond the jiroduced part of the basal joint ; its outer 

 margin is broadly rounded, but the inner margin is nearly straight ; the apex is broadly 

 truncate and indistinctly four-iobed — each lobe forming the base of a seta ; the outer 

 seta is stout and elongate, the next is short and very slender, the third seta is stout and 

 considerably longer than the outer one, while the inner seta is short and spiniform 

 (Pi. 38. fig. 3G). 



Caudal stylets equal to about two-thirds the length of the last abdominal segment 

 (PL 38. fig. 52). 



Habitat. Firth of Porth, off St. Monans. 



Remarks. The slender posterior foot-jaws and outer branches of the first foiu* paii-s of 

 swimming-feet serve to distinguish Ectinosoma teiiuipes from the other species described 

 in this memoir. 



EcTixcsoMA ATLANTICUM (Brady and Ptobertson). (PL 36. figs. 17 and 40; PL 37. 

 figs. 6, 23, 35, 50 ; PL 38. tigs. 11, IB, 38, 53.) 



1873. Microsetdla atlantica, B. & E.. (5), p. 130, pi. ix. figs. 11-16. 



1880. Ectinosoma atlanticum, Brady (3), voL ii. p. 13, pL xsxviii. figs. 11-19. 



1883. Ectinosoma atlanticum, Brady (4), p. 100, pL iv. figs. 10-14. 



1887. Ectinosoma atlanticum, Jules de Gueruc (8), p. 344. 



1891. Microsetdla atlantica, Scott (14), p. 302. 



1892. Microsetdla atlantica, Giesbrecht (7), p. 550, Taf. 44. 



1893. Ectinosoma atlanticum, I. C. Thompsou (16), p. 192, pi. xix. fig. 1. 



1894. Microsetdla atlantica, T. Scott (15), p. 91. 



58* 



