PULMONIGRADES. 679 



the ceatral part being thickest, and the under surface concave. 

 In some cases, cirri or tentacles, varying in length, form, and 

 number, are attached to the circumference. Some of the tenta- 

 cles have a colored spot (thought to be an eye) at their base. It 

 is quite certain that they are sensible to light. Some of the 

 smaller Medusse have been "known to shun a bright light, and 

 to sink into deep water to avoid it." The chief seat of touch 

 seems to be in the tentacula or cirri, which are also capable of 

 wonderful expansion and retraction. Many of these Medusse 

 make no sign when wounded in the umbrella or disk. The food, 

 consisting of small fishes and marine animals, is conveyed to the 

 mouth, not by the tentacles and cirri alone, but also probably 

 by contractions in the disk. These animals appear, in most cases, 

 to be bisexual, i. e., the two sexes are often united in the same 

 individual. Like some other lower organizations, they have 

 the power of producing their offspring by gemmation. " Fancy," 

 says Prof. Forbes, "an Elephant with a number of little 

 Elephants sprouting from his shoulders and thighs, bunches 

 of tusked monsters hanging epaulette- fashion from his flanks in 

 every state of advancement. The comparison seems grotesque 

 and absurd, but it really expresses what occurs among our 

 Naked-eyed Medusae." 



The phosphorescent or luminous appearance of the sea, and 

 which is shown in Southern latitudes with such brilliancy and 

 beauty, is to be chiefly ascribed to multitudes of these animals. 



FIRST ORDER. PULMONIGRADES. Lat. pulmo, a lung; gr&dior, 

 to advance.) MEDUSA or JELLY-FISH. 



The name of this order above given, refers to the contractile 

 and expansive power of the umbrella-shaped disk belonging to 

 the animal which it includes, and which in the exercise of this 

 power, resembles the breathing lungs. The order is also, with 

 reference to the umbrella or disk, named DISCOPHORA, (disk- 

 bearing.) As illustrating this order, we simply refer to the 

 genera and species noticed on the Chart, with the figures and 

 explanations there given. 



