136 BRITISH FRESHWATER FISHES 



is now unable to get beyond Worcester. In May 

 it appears in the lakes of Killarney, and I have little 

 doubt that the following passage from a History of 

 the County of Westmeath, written in 1682 by Sir 

 Henry Piers, refers to this fish : " About Lough 

 Tron and Lough Direvragh there is found, in the 

 month of May only, a small fish, without spot, of 

 almost the same shape as a herring a fish very 

 pleasant and delightful, but not taken in great 

 quantities ; the natives call it Goaske." 



Although the time of spawning of this species is 

 usually a little later than that of the Allis Shad, 

 there is a considerable overlapping, as is shown 

 by the not infrequent occurrence of hybrids, easily 

 recognized by the intermediate number of gill- 

 rakers. 



The growth of the Twaite in fresh water is pre- 

 cisely similar to that of the Allis ; the fry of 3 to 

 6 inches have fewer gill-rakers than the adult fish, 

 seventeen to twenty-four on the lower part of the 

 anterior branchial arch. As food the Twaite is held 

 in somewhat less estimation than the Allis Shad. 



It may be of interest to mention that Shad, like 

 Salmon, Trout, and Smelts, can live and breed in 

 fresh water without going to the sea ; the large lakes 

 of northern Italy are inhabited by a species of .Shad 

 (Clupea lacustris) which is a permanent resident. 

 This is a small and slender form, with the number of 

 scales and fin-rays as in the Twaite, but with the gill- 

 rakers not much less numerous than in small Allis 

 Shad; in three from Lake Garda, 4, 5, and 6 inches 

 long, I count respectively twenty-eight, thirty-two, 

 and thirty-six gill-rakers on the lower limb of the 

 anterior branchial arch. 



