neic and rare Crustacea from Scotland. 53 



angles of the same joints arc furnisliL-d with a lon,2f slender 

 seta ; tlie secondary branches are small and bear each four 

 «etje on the outer niaririn and apex, the apical seta belnj^ 

 lonijer than the others, while the upper two are small (H,i^. 22). 

 Cauchil stylets short ; the end ot" each stylet is prolonged 

 interiorly into a stout spiniform process, and bears a tew setie 

 exteriorly (Hg. 24). One ovisac, with a number of inode- 

 rat(!ly large ova. 



J/a/e. The male closely resembles the female in general 

 form, but the anterior anteunaj are eight-jointed and strongly 

 hinged, the second joint is much longer, and the thir 1 and 

 fifth shorter than any of the others. The fifth pair of tlioracic 

 feet are nearly as in the female ; the sixtli pair of appendages 

 (the apjiendages of the first abdominal segment) are small, 

 subquadrate in outline, and are each armed with a stout spine 

 and two seta3 on the apical margin, as shown in the drawing 

 (tig. 2.5). 



Habitat. In pools near low-water on the shore at Mussel- 

 burgh, Firth of Forth ; frequent. 



liemarks. The posterior foot-jaws with their extremely 

 long terminal claws form a prominent character in this 

 species and one by which it was readily distinguished from 

 the other Copepoda among which it occurred in the shore- 

 gathering from Musselburgh. The peculiar appearance of ttie 

 caudal stylets which is represented in the full-sized drawing 

 (fig. 12) is also a marked character; the seta^, as shown in 

 the drawing referred to, extend upwards at an obtuse angle 

 from the terminal spine, to which they seem to be attached 

 when viewed laterally ; and this peculiar appearance was 

 observed in all the specimens obtained. The structure of the 

 first pair of swimming-feet resembles somewhat that of the 

 same pair in Mtsochra Rohertsoni^ Brady, and in some 

 species of Attheyella. 



Mesochra MacIntosM, sp. n. 

 (PI. V. figs. 26, 27 ; PI. VI. tigs. 1-7.) 



Description of the Species. — Female. Length '6 millim. 

 (-j^ of an inch). Body elongate, cylindrical, very slender. 

 Anterior antennne rather longer than the tirst cephalothoracic 

 segment, eight-jointed, the j)eimltimate joint being con- 

 siderably shorter than any of the others, as shown by the 

 formula — 



1 1 . 22 . 16 . 11 . 8^ . 8^ . 4 . 9 



Number of tbe joints 1 2 li 4 6 6 7 8 



Proportional lenptlis of the joints. 



