186 Messrs. T, and k. Scott on Three 



The structure of tlie antennse and of the mouth-organs 

 resembles generally that of the same appendages in Stephos 

 gyrons and Stephos minor, though differing in some minor 

 details (PI. X. figs. 3-5). The first, second, third, and fourth 

 pairs of swimming-feet are also somewhat similar to those of 

 the same two species, but the last three pairs are propor- 

 tionally rather more slender and elongate (PI. XI. figs. 1-3). 

 The fifth pair are stout and in general appearance resemble 

 those of the other species, but they differ in the following 

 particulars : — the two members that compose the fifth pair, 

 though nearly equal in length, are somewhat unsymmetrical ; 

 in the (?) right foot the end-joint is rather longer than the 

 other and is of a broad knife-like shape, its inner margin is 

 even and nearly straight, while the outer is finely serrated 

 along the posterior half and curved inwards towards the apex ; 

 in the (?) left foot the end joint, which is about the same 

 length as the first, is dilated near the proximal end, and after 

 contracting somewhat abruptly on both sides tapers gradually 

 to the extremity, where it terminates in a moderately sharp 

 point (PI. X. %. 6). 



Description of the Male. — The male does not differ much 

 from the female except in the following particulars : — the 

 abdomen, which consists of five segments, is rather more 

 slender, and the first segment is not dilated. The fifth pair 

 of thoracic feet, though having a general resemblance to those 

 of the males of Stephos gyrans and Stephos minor, differ very 

 markedly in some of the structural details; in the right foot 

 the first and second joints are subequal and moderately short 

 and slender ; the third joint, which is also slender, is of con- 

 siderable length, being about one and a half times the entire 

 length of the first and second joints ; the last joint is long, 

 slender, and strongly falcate, so that it somewhat resembles a 

 reaping-hook, the convex side being outward, the basal 

 part of the joint is also produced inwardly into a process of a 

 triangular form ; the left foot terminates in a strongly dilated 

 appendage, which is armed with a large and dark horn- 

 coloured movable claw, distinctly bifid at the extremity ; there 

 are also, in addition to the claw, several elongate, flexuous, 

 and spiniform apical processes, as shown in the figure (PI. XI. 

 fig. 4) ; it is thus evident that the two members of the fifth 

 pair in the male form together a very powerful and efficient 

 grasping-organ. 



Bah. Kilbrennan Sound, Firth of Clyde, 1896; vicinity 

 of Otter Spit, Loch Fyne, 18ii7. 



Remarks. — The fifth pair of thoracic feet in both the males 

 and females of the species now described ai*e distinctly 



