94 BULLETIN OF THE LIVERPOOL MUSEUMS. 
The horn-like processes from the head, of which each individual is 
provided with three, radiate for some distance. In the case of the larger 
Penella the distance from tip to tip of two of the horns, is seven-eighths 
of an inch. 
The total length of the larger Penella, from the head to the tip of the 
plume-like tail, is 24 inches. In both cases the long filiform ovaries are 
wanting. 
A third small aperture in the abdominal wall, similar to the apertures 
caused by the parasites, was present about mid-way between them and the 
cloacal aperture. This may represent the point of the attachment of a 
third Penella, which had become detached, although no sign of any 
interference with the specimen could be detected. 
The entire absence of abdominal viscera is remarkable, if the information 
given with the specimen that the fish flew on board be true, and there is no 
reason to doubt it. As to the condition of the viscera in other similarly 
infested fishes nothing has been found in the literature at our disposal here. 
The Cirripeds, of which there is about a dozen on each Penella, are 
Conchoderma virgata. They vary in size from quite small individuals, with 
the capitulum of the size of a pin-head, to others five-eighths of an inch 
long, each with its capitulum three-eighths of an inch in length. 
Sir William Flower exhibited, in 1858, before the Zoological Society of 
London (P.Z.S 1858, p. 372), a specimen of Hxocetus volitans, from the South 
Atlantic, infested with a single Penella blainvillii, having its head buried in 
the muscles of the back, and to which also was attached a colony of the 
same Cirriped as on the specimen under notice. These two occurrences 
suggest that the presence of Conchoderma virgata living commensally on 
Penella blainwillii, is perhaps more than a chance association; and it 
would be of interest to obtain information of additonal instances of these 
two crustaceans living together in this way. 
Habitat of Gasterosteus pungitius, Linn.—In his Fishes of Great 
Britain, Mr. Day quotes Couch’s assertion that Gasterosteus pungitius ‘will 
not exist when confined in salt waters, however diluted such may be.’ 
We have living in the Aquarium, at the present time (July), a specimen of 
this fish captured in April last, in the undoubtedly brackish water ponds on 
the landward side of the Leasowe Embankament, on the Cheshire coast. 
It was captured along with Palemonetes varians, and on arrival at the 
Aquarium it was transferred to one of the salt-water tanks, in which the 
salinity of the water is always somewhat higher than that of fresh sea-water. 
The Stickleback has exhibited no signs of discomfort or inconvenience,— 
indeed, it has thriven well, and grown appreciably—during the months it 
has been in our tanks, where it still remains under observation, Dr. 
Giinther, it should be noted, observes that all the Sticklebacks ‘are able 
to exist in the sea.’ 
The First Feeding of Young Trout.—A method of feeding recently 
hatched trout lately adopted in the Aquarium, which has proved very 
successful, may be of interest to pisciculturists. Im April of the 
present year one thousand ova of Salmo irideus were obtained from 
Howietoun, near Stirling. Within a few days nearly all of them had 
hatched out safely, and there are now, in July, fully 60 per cent. of them 
alive in the tanks, many of them being over two inches in length. This 
represents a great improvement upon our previous trout-rearing experiences ; 
for at the corresponding age in former years, not more than 25 per cent. 
had survived. 
