SCYPHOMEDUSAE COLLECTED BY STEAMER " ALBATBOSS. ' ' 185 



torn until they become mature, when they often swim to the surface 

 to cast out their eggs and sperm. They are dull milky-yellow, or 

 livid in color, and their tentacles sting so sharply that they are com- 

 monly called " sea-wasps." None are known north of Cape Cod, 

 but they are well represented in the Tropics throughout the world. 



2. The Stauromedusae are attached forms which do not pulsate. 

 The body is pear-shaped or pyramidal and the jellyfish fastens itself 

 to seaweed or rocks by means of a stalk at the aboral end of the body. 

 There are usually 8 clusters of knobbed tentacles which are developed 

 at the pointed ends of eight marginal lobes, and 8 large " anchors " 

 or suckerlike clubs upon the margin may alternate with the tentacles. 

 These forms are confined to cold and temperate seas, and are known 

 from the Arctic and Antarctic Oceans, although they have never 

 been found in the Tropics. 



3. The Coronatae are usually deep-sea forms distinguished by their 

 peculiar dark purple or reddish-brown color, which is very charac- 

 teristic of the invertebrate animals of the deep sea, due possibly to 

 the fact that the red rays from the sun are rapidly absorbed as they 

 penetrate into the ocean, so that at depths greater that 1,000 fathoms 

 there is practically no red light, and here red-colored animals must 

 appear black and be well concealed in the general darkness of their 

 abysmal realm. The Coronatae are characterized by having a deep 

 ringlike furrow cutting into the thick gelatinous wall of the sides of 

 the umbrella; and peripheral to this are gelatinous thickenings 

 in the radii of the tentacles and sense-organs. The gelatinous wall 

 of the bell is much reduced in thickness at the ring-furrow, the thin 

 part acting as a hinge to permit the creature to close its bell during 

 contraction. These forms are common in the deep waters of the 

 Philippines, as indeed they are upon the bottom of all seas 500 

 fathoms or more in depth. Most of the species, such as Atolla and 

 Periphylla, do not normally come to the surface, but a closely allied 

 form, the little Nausithoe, is one of the most universally present sur- 

 face forms of all warm seas, while the mature Linuche occur in vast 

 numbers, all rapidly pulsating and resembling little brown thimbles, 

 the swarm often covering square miles of ocean in tropical regions. 



4. The Semaeostomata are the common large jellyfishes of our 

 coasts, such as Aurellia, Cyanea, and Dactylometra. They have ten- 

 tacles and a single cruciform mouth provided with veillike lips, 

 and there is no ring-furrow cutting into the surface of the umbrella, 

 such as is seen in the Coronatae. They are common in bays and 

 brackish estuaries : and are the largest and most conspicuous of all 

 jellyfishes in temperate regions. 



5. The Rhizostomae are the large jellyfishes of the East Indian 

 and tropical seas, where they are commonly as conspicuous as are the 



