of the Fishery Board for Scotland. 201 



Fifth pair of feet in both sexes rudimentary ; last abdominal segment not 

 spiniferous ; ovisacs two. 



Canuella perplexa, T. and A. Scott. (PL II. figs. 21-35.) 



1893. Canuella perplexa, T. and A. Scott ,' Ann. Scot. Nat. Hist., ; 



vol. ii. p. 92, pi. ii. figs. 1-3. 

 1880. Longipedia coronata, Brady (in part), 'Mon. Brit. Copep.,' 



vol. ii. p. 6, pi. xxxiv. figs. 3, 9 ; pi. xxxv. figs. 1, 3, 9. 

 1867. (?) Sunaristes paguri, Hesse, 'Ann. des Sci. Nat.,' 5th ser. 



(Zool.), vol. vii. p. 205, pi. 

 1884. (?) Longipedia paguri, W. M filler, ' Archiv. fur Naturg.,' 



Jahrgang 50, 1st Band, p. 19, pi. 13. 



Length (exclusive of caudal setae) 1'4 mm. (y^th of an inch). Body 

 seen from above elongate, nearly cylindrical, tapering slightly to the 

 posterior end ; forehead produced into a stout and somewhat conical 

 rostrum. Anterior antennae of the female stout, especially the basal 

 portion, curved, and indistinctly five-jointed, furnished with numerous 

 elongate setae, most of which are plumose ; two sensory filaments spring 

 from the third joint. In the male the middle joints of the anterior 

 antennae are narrower than the preceding joints, or than the one imme- 

 diately following. This joint, which is the penultimate one, is dilated, 

 while the last is small and hook-like — the two forming together an effi- 

 cient grasping organ. Primary branch of posterior antennae three-jointed, 

 the middle joint short ; secondary branch rather stouter than the other 

 and six-jointed, tapering slightly towards the posterior end ; the third 

 joint is somewhat longer than the other five ; the breadth of the first 

 joint is equal to about three times the length, and of the last to about 

 twice the length (fig. 23). Mouth organs nearly as in Longipedia 

 coronata. First pair of swimming feet also similar to those of Longipedia 

 coronata, but shorter, more robust, and armed with stouter spines and 

 longer plumose setae. The outer margin of the first joint of the outer 

 branch bears a pectinate fringe of spine-like setae immediately anterior to 

 the large spine, and the outer margins of the second and third joints of 

 the inner branch are similarly fringed. Both branches of the second pair 

 of swimming feet are of about equal length. First joint of the inner 

 branch very short, and armed on the lateral aspect with a stout conical 

 and tooth-like process, which reaches slightly beyond the end of the 

 next joint; the third joint in both branches is rather longer than the 

 combined length of the other two (fig. 28). The third and fourth pairs 

 are somewhat similar to those of Longipedia coronata. Fifth pair in 

 both sexes rudimentary, and consisting of a very small basal joint bearing 

 four setae ; the second seta from the inside is longer than the others and 

 plumose. Caudal stylets strongly divergent • length equal to rather more 

 than twice the breadth ; caudal setae comparatively short, scarcely equal 

 to three-fifths the length of the animal. Ovisacs broadly ovate ; their 

 transverse diameter about three-fifths of the length. 



This species is of frequent occurrence, especially in material dredged off 

 Musselburgh and in Largo Bay, but specimens with ovisacs are scarce. 



Canuella perplexa appears to be the form described in the monograph of 

 the British Copepoda as the female of Longipedia coronata. 



In 1867 Hesse described* a copepod he had discovered living in the 

 same shell with a Pagurus, and to which he gave the name of Sunaristes 

 paguri. This copepod resembles Canuella perplexa in some respects, but 

 the difference in habitat, the difference in size (Hesse states, loc. cit., that 

 Sunaristes is 5 mm. long, but this probably includes the tail setae), and 

 the difference in important structural details is so great that it seems 



* Ann. des Sc. Jfat., 5th ser. (Zoology), vol. vii. p. 205. 



