AMPHIPOPA. 263 



First uropods not reaching the end of the 2nd, outer rami half as long as the inner, 

 the upper margins of the rami in adults strongly serrate ; 2nd and 3rd uropods sub- 

 equal in extent, denticulate on the inner and spinous on the outer margins (fig. 20. 



up. 1 ). 



Length of adidt male, 5 millims. 



This species much resembles P. longimanus (Sp. Bate), the details above indicating 



the principal points of difference. As is usual with its congener on sandy coasts in 

 the British Seas and Mediterranean, it is found associated with a Synclielidium. 



Synchelidium, G. O. Sars, 1894. 

 Synclielidium brevicarpum (Sp. Bate). 



Kroyera brevicarpa, Bate and AYestwood, ' Brit. Sess. Crust.,' App., p. 508. 

 Cheval Paar, November, 1902, 1 specimen. Length 3 millims. 



Agrees with British examples even to the dark brown blotches on the 5th and 6th 

 segments of the mesosome. 



Tiron, Lilljep.org, 1865. 

 T. thompsoni,* n. sp. Plate IV., figs. 21. 

 Kondatchi Paar, 17th November, 1902, 1 specimen; Station LXVI. ; 1 female 

 with ova. 



Head rounded above, almost as long as the first 3 segments ; the front deflexed ; 

 ocular lobe rounded ; eyes obliterated. 



First mesosome segment almost as long as the next 2 and subequal to the 4th. 

 Segments of the pleon and first 2 of the urus slightly carinate, the carina? produced 

 to teeth which are very conspicuous on the urus, as in Tiron acanthurus, Lillje. 



Upper antennae reaching the end of the peduncle of the lower ; 1st joint twice as 

 wide and lono- as the 2nd, with a long distal spine ; 3rd much narrower and almost 

 as lono- as the 1st ; flagellum 6-jointed ; appendage reaching the end of the 2nd joint 

 of the flagellum, 3-jointed, the first 2 subequal, the last minute (fig. 21. ant, 1 ). 



Lower antenna? : 1st joint thick, about half as long as the 2nd, which is subequal 

 to the 3rd ; flagellum 6-jointed, shorter than the 2 last joints of the peduncle (fig. 21. 



ant. 2 ). 



Maxillipeds : inner plate reaching a little beyond the end of the 1st joints of the 

 palp, the top rounded with plumose submarginal seta? ; outer plate membranous, the 

 surface concave, margins irregular and setose ; 1st joint of the palp shorter than the 

 2nd, which is swollen and about as long as the 3rd ; dactylus slightly curved, acute 

 (fig. 21. rnxp.). 



First gnathopods : side-plates widened below, rounded in front, with about 6 sub- 

 marginal seta? on the lower margin ; 1st joint shorter than the next 3, widening 

 distally ; wrist rather longer and considerably wider than the hand to which it 



* Named after my late friend and fellow-worker, Mr. Isaac C. Thompson, F.L.S. 



