148 BEITISH COPEPODA. 



ciliated ; the external ovate joint is fringed with cilia, 

 and bears also five ciliated apical setae of unequal 

 length ; in the male (fig. 14) the basal joint is obsolete, 

 and the outer plate, though more angular, is very 

 similar to that of the female. The second and third 

 abdominal rings (fig. 15) are denticulated along the 

 hinder border and at the angles. Caudal segments 

 very short and broad. Inner tail seta about twice as 

 long as the outer, and finely aculeate beyond the 

 middle. Length -^th of an inch (-98 mm.). 



This fine species is of common occurrence in the 

 littoral and laminarian zones, and is likewise frequently 

 taken by the dredge, and by the towing-net in the open 

 sea. Different examples vary very much in amount of 

 setiferous and spinous armature (especially in the fifth 

 pair of feet) as well as in slenderness or robustness of 

 build, and it seems to me that it is on mere degrees 

 of variation in these respects that the species gracilis, 

 Glaus, and elongatus, Boeck, have been founded. I have 

 often met with examples which might have been referred 

 to one or other of these species, but have been unable to 

 find any permanent and trustworthy diagnostic mark 

 separating them from the typical H. chelifer. I there- 

 fore prefer to consider the two as varieties only. The 

 foot, represented in Plate LXY, fig. 10, and the foot- 

 jaw in fig. 8, are, I believe, well-marked examples of 

 those organs in the gracilis form, specimens of which 

 from the Mediterranean Professor Glaus has been 

 good enough to send me. It is, however, only right 

 to add that Dr. Glaus has examined the subject with 

 great care, comparing specimens from widely separated 



