new and rare Crustacea from Scotland. 53 



angles of the same joints are furnished with a long slender 

 seta; the secondary branches are small and bear each four 

 seta? on the outer margin and apex, the apical seta being 

 longer than the others, while the upper two are small (fig. 22) . 

 Caudal stylets short ; the end of each stylet is prolonged 

 interiorly into a stout spiniform process, and bears a few setse 

 exteriorly (fig. 24), One ovisac, with a number of mode- 

 rately large ova. 



Male. The male closely resembles the female in general 

 form, but the anterior antennce are eight^jointed and strongly 

 hinged, the second joint is much longer, and the third and 

 fifth siiorter than any of the others. The fifth pair of thoracic 

 feet are nearly as in the female ,• the sixth pair of appendages 

 (the appendages 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 

 (fig. 23). 



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

 burgh, Firth of Forth ; frequent. 



Remarks. 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 the 

 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 Mesochra Robertsoni, Brady, and in some 

 species of Attheyella. 



Mesochra Maclntoshi, sp. n. 

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



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

 {^ of an inch). Body elongate, cylindrical, very slender. 

 Anterior antennae rather longer than the first cephalothoractc 

 segment, eight-jointed, the penultimate joint being con- 

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

 formula — 



Proportional lengths of the joints . . 11 . 22 . 16 . 11 . 8| . 8| . 4 . 9 ^ 

 Number of the joints 12345078 



