of the Fishery Board for Scotland. 129 



and outer branches are about equal in length, and in this pair, while the 

 first and second joints of the inner branches are each provided with a 

 single seta on their inner margin, the third joint bears two setae. On the 

 other hand, the inner margins of only the second and third joints are each 

 provided with one seta (fig. 26). In the fourth pair the inner branches 

 are rather shorter than the outer, and the armature of the inner margins 

 of both branches resembles that of the third pair except that the last joint 

 of the inner branches is furnished with one instead of two setae on its 

 inner edge (fig. 27). 



The fifth pair are moderately large and foliaceous ; the inner produced 

 portion of the basal joint is generally of a sub-cylindrical form, but the 

 distal end tapers to a blunt-pointed apex from which spring two setae of 

 moderate but unequal length ; the distal half of the inner margin carries 

 also two moderately stout spines, as well as an elongated seta, as shown 

 in the drawing (fig. 29). The secondary joint has a sub-ovate outline, and 

 its extremity extends somewhat beyond the end of the inner produced 

 portion of the basal joint ; it is nearly twice as long as broad and is fur- 

 nished with five setae which are arranged round the distal end of the joint 

 as shown by fig. 9 already referred to. 



The male somewhat resembles the female, but there are the following 

 important differences in addition to the usual modification in the 

 antennules : — (1) The inner branches of the second pair of thoracic feet are 

 distinctly modified ; these branches in the male appear to be only two- 

 jointed, the first joint is moderately stout but short, the second extends 

 into a prolonged and stout tapering process which reaches considerably 

 beyond the ends of the outer branches ; the first joint also bears one seta on 

 its inner edge, but the elongated second joint is furnished with two (fig. 28V 



The fifth feet in the male are small ; the inner portion of the basal 

 joint is broadly cone-shaped and carries two apical setae ; the secondary 

 joint is moderately broad and of a somewhat ovate form, and is provided 

 with five setae, the two setae on the outer margin are short and spinifomi, 

 the apical seta is elongated and slender, while the two on the inner edge 

 are moderately stout and appear to be plumose (fig. 30). There is also a 

 small trispinous appendage on the first segment of the abdomen . 



Habitat. — Off Musselburgh, Firth of Forth ; not common. 



Remarks. — This small species seems to agree better with Dactylopus 

 minutus, Claus, than with any other member of the genus, but it differs 

 distinctly from that species by the structure of the antennules and of the 

 fifth pair of feet in the female, and by the peculiar character of the second 

 Dair of feet in the male. 



Genus Thalestris, Claus (1863;. 



Several species belonging to the genus Thalestris have been observed 

 in gatherings recently examined, and the following are now recorder! for 

 the first time from the Firth of Forth. 



Thalestris peltata, Boeck. 



1864. Anemophia peltata, Boeck. Oversigt Norges Copepoder, 



p. 45. 

 1880. Thalestris peltata, Brady, Brit. Copep., vol. ii., p. 138, 



pi. liii., figs. 11-19. 

 1895. Thalestris peltata, T. and A. Scott, Ann. Nat. Hist. (6), 



vol. xiv.; p. 351, pi. xv., figs. 11-15.; pi. xvi., figs. 1-8. 



The somewhat aberrant species of Thalestris was obtained off Mussel- 

 burgh in shallow water (3-4 fathoms). Thalestris peltata appears to be a 

 I 



