126 GILLAROO TROUT. 



physiologist, John Hnnter. The muscular walls of the Gillaroo are so strong that they have 

 been supposed to perform to a certain extent the function of a gizzard. Though such a 

 function was denied by Watson and by Hunter, I think that this organ, with its thickened 

 membrane is, to a small extent, a quasi-gizzard, analogous to that of birds ; this is rendered 

 probable from the fact that, in another genus of fishes {Afi/gil) there exists a modification of 

 the stomach which seems to give it the true character of a gizzard. The essential characters 

 of a gizzard are mainly these two : first, a power and motion fit for trituration, and secondly 

 a cuticular horny lining. Now, Professor Owen has shown that in the Mullets {Mito^il) this latter 

 structure does exist in the stomach of the Mullet, as a distinct layer of rough and separable 

 cuticle. "The modification which gives the stomach the true character of a gizzard, is best 

 seen," writes Professor Owen, "in the Mullets, [Mugil). The cardiac portion here forms a long 

 ciil-dc-sac; the pyloric part is continued from the cardiac end of this at right angles, and is of 

 a conical figure externally; but the cavity within is reduced almost to a linear fissure by the 

 great development of the muscular parieties, which are an inch thick at the base of the cone, 

 and this part is lined by a thick horny epithelium." — -{Aiiaf. of Vcrtcb. vol. i. p. 418.) With regard 

 to the first essential point — triturating power and motion — there seems to be no doubt that 

 such does exist in the stomachs of some, probably most, fishes. I here quote our great 

 anatomist again. "The muscular action of a fish's stomach consists of vermicular contractions, 

 creeping slowly in continuous succession from the cardia to the pylorus, and impressing a two- 

 fold gyratory motion on the contents ; so that, while some portions are proceeding to the 

 pylorus, other portions are returning towards the cardia. More direct constrictive and dilative 

 movements occur, with intervals of repose, at both the orifices, the vital contraction being 

 antagonized by pressure from within. The pylorus has the power, very evidently, of controlling 

 that pressure, and only portions of completely comminuted and digested food (chyme) are 

 permitted to pass into the intestine." — (P. 419.) The food of the Gillaroo Trout consists for 

 the most part of various molluscs, which it picks off the rocks and stones in the lakes inhabited 

 by these fish, and there can be little if any doubt, that the strong muscular parieties of the 

 stomach act in breaking up the .shells of some of the molluscs on which they feed ; and 

 although the inner cavity of the stomach of the Gillaroo is destitute of a thick horny epithe- 

 lium as seen in the Mullet — for the whole cavity is lined with a fine villous coat — still I 

 doubt not that this organ does possess some power of grinding. 



I have caught in company with Lieutenant Colonel Masefield, several of these fi.sh in 

 Lough Melvin, in July, 1878; they are a very plucky fish, and when hooked fight hard to get 

 away. The beautiful bright peach and light orange colour of their sides reveals the species, 

 as it approaches to seize the fly. The Gillaroo proceeds more leisurely and apparently more 

 cautiously than either the Common Trout or the Black- Fin; it seems at first to hesitate at 

 the flv, but turning itself on its side, and at length being satisfied all is right, it rises vigo- 

 rously, and generally gets well hooked ; and if the angler has a good fish, of two pounds or 

 so, on his line, I can assure him, a Gillaroo will give most excellent sport, and where there 

 are weeds, such as the potaniogetons with their tough stems, unless the tackle be good, the 

 chances are the fish will succeed eventually in avoiding the landing-net. 



The boatmen at Lough Melvin say that the Gillaroo spawns on the shallower parts of the 

 lake, and does not ascend the rivers for that purpo.se. As to size, the Gillaroo in the Irish 

 lakes often weighs three, four, or five pounds. Thompson was informed that specimens weighing 

 twelve pounds are sometimes taken at Lough Neagh, and Couch states that they have been 

 known to attain the size of nearly thirty inches, with a weight of about twenty pounds. The 

 largest I succeeded in taking did not weigh more than two pounds, but a fish of even a 

 pound weight is quite an angler's prize, owing to the sport which it is able to afford. In 

 memoranda of Mr. Walsh, F.R.S., {Pliilosoph. Transact., quoted above, p. 119), dated Killaloe, 

 Oct. ist., 1773, "Innkeeper's account," it is stated that "the gizzard of a Gillaroo Trout is 



