20 POPULAR SCIENCE MONTHLY. 



a series of huge triton snails and the clustered eggs of cuttlefish. 

 In another tank a bank of sea anemones exemplifies the large and 

 gaudy forms common to southern waters buff, orange, yellow, 

 and vermilion and there may be corals in the background, and 

 a spectral forest of sea fans in white and violet, with a precious 

 fringe of pink coral flowering out in yellow, starlike polyps. 

 There may, again, be in a neighboring tank a host of ascidians, 

 those curiously degenerate vertebrates whose stock could not have 

 been widely unlike the ancestral stem of the fishes. Delicate, 

 transparent, solitary forms, like the lanky Ciona, contrast with the 

 deeply crimson Cy7iihia and the huge and mottled masses of many 

 compound forms. Swimming about them may be chains of Salpa, 

 and occasionally a number of Amphioxus, the latter to be seen 

 only from time to time as they burrow out of the sandy bottom, 

 flurry about as if in sudden fright, and quickly disappear. Va- 

 riety is one of the striking characters of the arrangement of 

 neighboring tanks. In one, brilliant forms outvie the colors of 

 their neighbors. In another are examples of the closest mimicry 

 of animals to their surroundings, where the stranger has often 

 to examine long before in the seemingly empty tank he can deter- 

 mine on every side the hidden forms. Thus one by one will come 

 into his view the rays and flounders, whose colors render them 

 almost indistinguishable from the gravelly bottom ; next he will 

 see the upturned eyes of the curious stargazer, which lies almost 

 buried in the sand ; then a series of mottled crustaceans, wedged 

 about in the rocky background, or an occasional crab which 

 wanders cautiously about, carrying a protective garden of sea- 

 weeds on his broad, flattened back. Near by will be odd-looking 

 pipefishes and the sea horses, poised motionless in mimicry of 

 the rough stems of the seaweeds. In a larger tank, sea turtles 

 float sluggishly about, and coiling amid broken earthen jars are 

 the fierce-looking, snakelike, sharp- jawed murries, to suggest 

 Roman dinners and the slave-eating experiments of the lordly 

 Pollio. 



The aeration of the aquaria is secured effectively by streams 

 of air which are forced in at the water surface and subdivided 

 into bright clouds of minute silvery bubbles. The tanks are 

 cared for from the rear passageways, and the attendants are rarely 

 seen, although it is the constant attention in the arrangement and 

 the restocking of the tanks that has gained the aquarium its 

 well-earned success. Illustrated catalogues in French, German, 

 English, and Italian enable the stranger better to appreciate 

 his visit. 



Amsterdam. The Amsterdam Aquarium is the most recent 

 of the larger aquariums in Europe, dating from 1880. It was then 

 opened, under the directorship of Dr. G. F. Westerman, as an ad- 



