‘ of the Fishery Board for Scotland. 201 
i ae So 
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. 11. p. 92, pl. 1. figs. 1-3. 
1880. Longipedia coronata, Brady (in part), ‘Mon. Brit. Copep.,’ 
woe i: pO ph xxxiv. figs. 3,9); pl swsexy- ties.) Poss 9: 
1867. (2) Sunaristes paguri, Hesse, ‘Ann. des Sci. Nat.,’ 5th ser. 
(Zool.), vol. vii. p. 205, pl. 
1884. (2) Longipedia paguirt, W. Miiller, ‘ Archiv. ftir Naturg.,’ 
Jabrgang 50, lst Band, p. 19, pl. 13. 
Length (exclusive of caudal setz) 1-4 mm. (4th 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 antenne of the female stout, especially the basal 
portion, curved, and indistinctly fivejointed, furnished with numerous 
elongate sete, most of which are plumose; two sensory filaments spring 
from the third joint. In the male the middle joints of the anterior 
antennz are narrower than the preceding joints, or than the one 1mme- 
diately following. ‘This joint, which is the penultimate one, is dilated, 
while the last is small and hook-like—the two forming together an efli- 
cient grasping organ. Primary branch of posterior antenne 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 Lonyipedia 
coronata. First pair of swimming feet also similar to those of Longipedia 
coronata, but shorter, more robusi, and armed with stouter spines and 
longer plumose setz. ‘The outer margin of the first jot of the outer 
branch bears a pectinate fringe of spine-like setze 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 setz ; 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 sete 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 coronuta. 
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 
pagurt. 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 setz), and 
| the difference in important structural details is so great that it seems 
* Ann. des Sc. Nat., 5th ser. (Zoology), vol. vii. p, 205. 
