The British Guiana Museum. 211 
as well as its scientific name is based ; this modification 
has evidently been brought about by the curious method of 
swimming, part of the head being in water and part in air, 
the eyes being placed so as to command both elements : 
the pacamah (Batrachus sp., no. 27^ a common and 
ugly fish, with a very large and broad, frog-like head, 
living chiefly in holes in the mud and capable of inflicting 
a severe bite: the hassar (nos. 31 and 12), a curiously 
helmetedand very common Siluroid, possessingaconsider- 
able power of endurance out of its normal element, and 
capable of progression on land by means of its strong fins ; 
these fishes construe! nests for their young : the striking- 
looking logo-logo (Gymnotus sp., no. 46^ : the gilbacker 
(Stlurus parkeri, no. 40/ a Siluroid of gorgeous colour- 
ing and of great economic importance ; the flesh is useful 
as food and comparable to veal, while the swim-bladder, 
when dried, forms a most useful glue : the sea-hassar 
(Callichthys sp. y no. 4.1) a quaint-looking and curiously 
helmeted Siluroid : the flounder (no. 22) a fish which, 
like the other members of the family Pleuronectidde 
generally, has undergone a curious modification, by which 
the body has been extremely flattened from side to side, 
the fish then swimming with one side, either the right or 
left (and not the true back), uppermost, both eyes 
being situated on one side : the snook (Centropomus 
undecimalis, no. 28J a. tropical perch, highly esteemed 
as food : and the perai (Serrasalmo niger^ no. 24^ a salmon 
of evil repute, abounding in the upper parts of the 
rivers, of insatiable rapacity, and hence correspondingly 
dreaded owing to its dangerous biting power — the jaws 
being furnished with large, triangular, and extremely sharp, 
cutting teeth ; these jaws are, or were, necessary adjuncts 
