OF BEITISH FORMS, lxxxvii 



We have now to consider whether fresh-water fishes in their distribution 

 lend any countenance to the theory that Ireland was formerly united to 

 continental Europe; also that a great portion of Great Britain became 

 submerged, but a re-elevation of land occurred ; and finally that Ireland was 

 separated from Great Britain, and subsequently the Straits of Dover opened. 



Among the nineteen British genera thirteen are present in Ireland : Lota, 

 Barbus, and Alburjius, local in England and unknown in Scotland, are 

 absent from Ireland; so likewise are the local races of Thymallus, introduced 

 north of the Tweed during recent years, while the only recorded Acer'ina in 

 Scotland, is one specimen said to have been obtained off Troup Head in Banff- 

 shire, possibly an error. Leaving our common bull-head, Gottus, as an absentee 

 from Ireland, where, however, Yarrell believed it to be^ found : Wallace's 

 contention that the distribution of the species of our Salmonida) confirms 

 the view that the races of fresh-water fish in Ireland differ from those in 

 Britain, is founded on two mistakes: first, he considers varieties as species; 

 secondly, even were they species, he mis-states where • they are found. If, 

 however, we turn to the Leucisci, we do find, the roach, L. rutilus, the chub, 

 L. cephalus, and the dace, L. vulgaris, to be absent from Ireland,, and also 

 more or less from Scotland unless introduced. Fresh-water fishes, while they 

 do not refute the disseverance of Ireland from Great Britain previous to the 

 division of the latter -from continental Europe, do not add any material 

 confirmation to the statement. 



Respecting the geographical distribution* .of our marine forms, I have , 

 .alluded to it when describing the families and genera; and consequently 

 shall limit my remarks first as to whether similar .species exist in distant 

 regions of the globe, and secondly, how they disperse. M. Valenciennes, 

 in 1821 ("Mem. du Mus.," xi, p. 265), drew attention . to the- great 

 resemblance that existed between the fishes inhabiting the Mediterranean 

 and those. of the seas of South Africa; while Dr. Keller has ascertained' 



* Errors iu the geographical distribution of species are not infrequently due to insufficient care' 

 having been exercised in testing the accuracy of statements as to from whence the specimen had 

 been obtained. An example of sucking-fish (Echeneis)wa,s sent me in a bottle of spirits as having 

 been brawled at the Norc in May, 18S0, which was so far correct that it had been thus taken, bottle 

 and all. It is easy to perceive how accidents might occur trawling such examples as the one I now 

 record. Had the bottle been broken and a sucking-fish found in a trawl at the mouth of the 

 Thames, it might have obtained access into a local collection, and when the species became 

 recognized it would most truly have been asserted to have been captured at Southend. Turton has 

 rd us respecting the North American bony pike (Jjepidosteus ossev.s') i that " it is rarely found 

 on the Sussex coast," probably because Berkeuhout, in his " Outlines of Natural History," records 

 one two feet Long : also Stewart (_" Elements," i, page 37-1) has remarked upon its occurrence in 

 the Frith of Forth. If these specimens were received they may have come from a wreck, or were 

 perhaps thrown overboard by a passenger or sailor. Even in 1880 the tropical Ilolacanthus tricolor 

 was erroneously asserted by Dr. Gunther to have been obtained at the Island of Lewes (vol. i, p. 41). 



