391 Part III. — Eighteenth Annual Report 



Remarks. — This copepod lias a superficial resemblance to a small 

 form, with six-jointed antennules, described by T. and A. Scott under the 

 name of (?) Canthocam/ptus parvus .* Like that form, the copepod now 

 described has the antennules six-jointed, and the inner branches of the 

 second, third, and fourth pairs of thoracic feet two-jointed, but the 

 proportional lengths of the joints of the antennules are different, and the 

 caudal furca, which in Canthocamptus parvus are very short, are in the 

 species now described as long as the anal segment. No males have been 

 observed. 



Habitat. — Moray Firth ; obtained amongst some dredged material. 



Mesochra spinicauda, T. and A. Scott. 



1895. Mesochra spinicauda, T. and A. Scott, Ann. and Mag. 

 Nat. Hist. (6), vol. xv., p. 52, PL V., figs. 12-25. 



This was one of several curious species that were found in shore pools 

 at Musselburgh, Firth of Forth ; the pools occurred between tide marks, 

 but nearer low water, and were surrounded on all sides by beds of 

 mussels. I am now able to record the occurrence of the species in shore 

 pools near Millport, Cumbrae; it was obtained in some gatherings 

 collected by hand-net on May 6th, 1899. 



Tetragoniceps (?) malleolata, Brady. (PI. XIV., figs. 9-17.) 



1880. Tetragoniceps malleolata, Brady, Mon. Brit. Copep., vol. 

 ii., p. 66, Pl.LXXVIIL, figs. 1-11. 



In Part III. of the Tenth Annual Report of the Fishery Board for 

 Scotland (1892), p. 252, f I recorded the occurrence of a species of 

 copepod which had been obtained in the Firth of Forth off St. Monans, 

 and which I had ascribed to Tetragoniceps malleolata, G. S. Brady. I 

 then pointed out, however, that this copepod, while agreeing in most 

 points with the genus and species named, differed in so far as it 

 possessed nine-jointed instead of eight-jointed antennules, and in the fifth 

 pair of thoracic feet being two-jointed instead of being composed of only 

 one joint. At the time the record was published, I was quite avrare that 

 the second of these two differences was, in view of the definition of the 

 genus, a somewhat important one, but considered that, as the copepod 

 referred to resembled the species named in almost all the other details of 

 structure, it was better to ascribe it to that species rather than to 

 institute a new genus or species for its reception. 



During the past year I have obtained, in some dredged material from 

 the Firth of Forth collected in 1896, but only recently examined, a few 

 more specimens of the copepod referred to above, as well as of another 

 and somewhat closely allied form that appears to be undescribed. 



When the supposed Tetragoniceps malleolata was recorded in the 

 Tenth Annual Report no detailed description of the form was given • a 

 reference to the two principal points of difference was considered to be at 

 that time all that was necessary for the identification of the form. The 

 occurrence, however, of the closely allied and apparently undescribed 

 species which I have alluded to makes it desirable that a description of both 

 forms should now be given, so that the differences that have been observed 

 between them may be more clearly indicated. 



It may be considered doubtful whether the two forms to be described 

 should be retained in the genus Tetragoniceps, but for the present, at 



* Ann. and Mag. Nat. Hist. (6), vol. xviii., p. 6, PI. II., figs. 14-22 (1896). 

 t Additions to the Fauna of the Firth of Forth, Part IV. 



