AND OTHER BRITISH PRAWNS. Ill 



with them. On the other hand, the general frequency of occur- 

 rence of the various number of teeth differs so greatly that 

 I am of opinion that a real local difference is shown. De Man's 

 figures are as follows : — 



Dorsal teeth :• 

 Individuals : 



Yentral teeth 



Individuals: 1-06 7o 2-1 7o 67 7o 29 7o 



Mandible palp. — Three-jointed, the second joint about half as 

 long as the third in the adult, but only one-third of it in young 

 specimens. 



Antennule. — The short flagellum is two-thirds, rarely a little 

 more, of the length of the peduncle, and is fused to the longer 

 flagellum by about one-third of its length. Taking the average 

 of seven measurements, and regarding the total length as 100, 

 the result is as follows : — Fused part 31 ; free part 69 ; the free 

 part being therefore about twice the length of the fused part. 



Second leg. — The second leg readies beyond the antennal scale 

 by the whole of the chela and usually about one-third of the 

 carpus. The dactylus is visually nearly one-third of the length 

 of the whole chela, but the proportion is very variable, and it 

 may sometimes be nearly equal to the palm. The chela of this 

 leg does not therefore provide means for distinguishing this 

 species from L. adspersus. The chela exceeds the length of the 

 carpus by about one-tenth, and the carpus is usually slightly 

 longer than the merus. Carpus and raerus are, however, so 

 nearly equal that very careful measurement is necessary to 

 determine which is the longer. An average of 20 measurements 

 gave the figures : — Carpus 101 ; merus 100 ! 



Distribution. — L. longirostris has been recorded from Liberia 

 (Rathbun), Corsica, and the French coast at Noirmoutier. It 

 has also been found in the River Gironde as far up as Bordeaux, 

 and in the Loire up to Yertou. (30 miles). In the British Museum 

 there are specimens from near Seville, about 50 miles up the 

 River Guadalquivir. De Man found it to be common at cei'tain 

 points on the Dutch coast. In the estuary of the Meuse it is 

 abundant in the Hollandsch Diep, and has been taken as far up 

 as Werkendam, which is just above the Biesbosch. It occurs 

 also in the Zuider Zee, the Ij, in the Rhine near Katwijk, and 

 in the Scheldt up to Antwerp. It therefore inhabits estuarine 

 regions, but within the range of sea-water. De Man only records 

 L. squilla from the outer Scheldt on the Zeeland coasts, so that it 

 seems to be replaced in Holland by L. longirostris. 



In Norfolk this prawn is abundant in Oulton Broad, and in 

 Breydon Water at certain times, and it is known to local fisher- 

 men as the " Jack Shrimp " or " White Prawn." In Oulton it is 

 used as bait for perch-fishing, but not for food. In Breydon it is 

 said to be more numerous when there is much fresh water passing 



