ISOPODA. 23 



dorsal shield is small and inconspicuous. The carpus is scarcely as long and much 

 more slender, the propodus is longer and still more slender, the dactylus is rather short. 

 There are but few spines properly so called on this appendage, the merus, carpus 

 and dactylus bear several as distal fringes or on the ventral surface of the joint, 

 which are of a distinctly spinous character. The setse on the ischium, except those 

 dorsally situated, are indistinctly plumose, elsewhere they are simple. 



A single specimen of this species, a female, was taken in the traps in Winter 

 Quarters, 29. 8. 03. in 25 fms. Another, mutilated, example was found in a seal's 

 stomach, 31st January, 1903. 



SEROLIS. 



This genus was established by Leach in 1818 and now contains twenty-four species, 

 nearly all of which are from the southern hemisphere. 



SEROLIS TRILOBITOIDES. 

 (Plate IV.) 



fri-tilis trilolitoides Eights (6), pp. 53-57. 



Bronyniartia cornuta Studer (17), pp. 21-24 ; Beddard (18), pp. 49-53. 



Specific characters : 



Body broadly ovate, with large serrated epimera curved backwards, the sixth thoracic segment 

 not extending much beyond the insertion of the uropoda. 



Cephalosome with well-developed eyes, two swellings' between them having the posterior margin 

 three-lobed as the adult condition is reached. 



Urosome pentagonal, margin dentate from the insertion of the uropoda, a median dentate keel 

 terminating in a short caudal spine. On each side an oblique ridge terminating in a tooth near the 

 insertion of the uropoda. Two teeth separated by a small recess in the middle line before the 

 beginning of the median keel. 



Special spines on the propodus of the second thoracic appendage consisting of sensory teeth 

 alternating with broad leaf-like sensory structures, of which the blade is unequally developed on the 

 two sides of the shaft. 



The body is nearly circular, the largest specimen measures 48 mm. in length and 

 43 mm. in width. If the basal joints of the antennae, which are directed forwards, be 

 included the length of the animal is increased to 53 mm. The epimera are large with 

 a finely serrated external margin, all more or less curved backwards ; those of the 

 sixth thoracic segment reaching nearly to the end of the caudal shield. Those of the 

 abdominal segments terminate just in front of this and are subequal. The posterior 

 margin of each of the thoracic epimera bears a tubercular swelling at about one-third 

 of its length. The urosome is pentagonal in outline, its free margin from the 

 insertion of the uropoda is beset with numerous pointed teeth and terminates in the 

 middle line in a stout spine. In the larger specimen this is broken, but, judging from 

 the smaller one, it should be about 3 mm. long. The middle line of the urosome is 

 marked by a prominent ridge bearing seven teeth of variable size ; the first is the 

 largest and the posterior ones are the smallest. In front of this ridge, at the junction 

 of the caudal shield with the third abdominal segment, there is a prominent lip which 



