of the Fishery Board for Scotland. 297 



times the length of the next one ; the second, third, and fourth segments 

 sub-equal in length, l)ut the fifth is rather shorter than the one immedi- 

 ately preceding. The abdomen is very short, being only about a fifth of 

 the entire length of the cephalothorax ; the genital scgnaent exceeds the 

 combined lenghts of the next two as shown in the full-size drawing 



(fig- !)• 



The antennult's are short but moderately stout, and they ta[)er towards 



the distal end ; the first and second joints are considerably dilated, and 



together are equal to more than half the entire length of the antennules ; 



the curved spine at the distal end of the second joint is much smaller 



than the spine similar to it on the second joints of the antennules of 



Eudadylina acuta (fig. 2). 



The antennae are somewhat similar to the same appendages in 

 Eudaclylina acuta, but they want the stout tooth-like spines on the inner 

 aspect of the first and second joints, and there appears to be only one 

 claw-like spine at the end of the last joint (fig. 4). 



The mandibles, maxillae, and other mouth appendages are somewhat 

 similar to those of Eudnctylina acuta (or Kudacti/lina similis). 



In the first four pairs of thoracic feet, the inner branches are all two- 

 jointed; but while the outer branches of the first pair consist apparently 

 of one joint, those of the next three pairs appear to be composed of 

 three joints ; all the four pairs are short and robust. The inner branches 

 of the first pair are armed with a number of very short but stout spines, 

 chiefly on the exterior margins ; the outer branches, wdiich are shorter 

 than the inner ones, are fringed on the exterior edge with minute sette ; a 

 small spine springs from a notch slightly posterior to the middle of the 

 same margin, while two or three small spiniform setse terminate the joint, 

 as shown in the drawing (fig. 5). 



In the second pair the inner brauches are somewhat similar to, but 

 rather stouter than, the inner branches of the first pair ; the outer 

 branches are somewhat indistinctly three-jointed, and only slightly longer 

 than the inner branches, and both branches are fringed on the exterior 

 edge with small spines ; the outer margin of the first basal joint is also 

 similarly fringed, while small spines are scattered sparingly over portions 

 of the surface of all the joints as shown in the drawing (fig. 6). 



The remaining two pairs are somewhat similar in structure to the second 

 pair, but are, comparatively, rather stouter, they are also less spiniferous 

 than that pair (fig. 7). 



The fifth pair resemble those of Eudactijlina acuta, but differ slightly 

 in their form and armature (fig. 8). 



The caudal furca, which are not much longer than the last abdominal 

 segment, are somewhat narrower than those of Eudactylina acuta — the 

 width being only equal to about half the length ; two short spines spring 

 from the outer margins of each f ureal joint and the spiniform selK from 

 the apex, the middle apical seta being the longest (fig. 9). 



Habitat. — On the gills of the Piked Dog-fish, Squalus acanthius, L., 

 captured in Beaumaris Bay, on September 26th, 1901. I am indebted 

 to my son for the privilege of describing this species, and for the illus- 

 trative drawings. This Eudactylina appears to be of frequent occurrence 

 on the gills of S. acanthius, captured in the Irish Sea, and may probably 

 also be obtained on the gills of Scottish specimens of the fish. It may 

 be noted in passing that Eudactylina acuta has been recorded both from 

 the Angel-fish and the Piked Dog-fish (see Professor van Beneden's 

 memoirs already referred to) ; perhaps the two forais may have been 

 mixed up under the one name ; but whether that be so or not, the 

 parasites from the two fishes named, which have been examined by myself 

 and my son, appear to be distinct, 



