194 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



'a O 



• o 



LINUCHE UNGUICULATA, var. AQUILA Mayer. 



Linerges aquila Haeckel, 1880, Syst. der Medusen, p. 496. 



Linuche aquila Mayek, 1910, Medusae of the World, vol. 3, p. 560, figs. 356 



B and C. 

 Linuche unguiculata Vanhoffen, 1913, Zoologischen Jahrbiichern, Suppl. 



11, Heft 3, p. 429. 

 Linuche ungiculata forma aquila Mayer, 1915, Publication No. 212, Carnegie 



Institution of Washington, p. 174, fig. 1, B and O. 



This variety is widely distributed over the tropical Pacific and is 



closely related to the tropical Atlantic L. unguiculata, with which it 



is identical in form and dimensions, being about 13 mm. high and 16 



mm. wide. It has 48 wartlike protuberances upon the subumbrella 



arranged in two rows instead of in three, as is commonly the case 



in the Atlantic medusa. Eight 

 On • 



of the subumbrella sacs in the 



variety aquila alternate with 

 the gonads and eight arise 

 from the sides of the gonads 

 themselves. Thus, in the Pa- 

 cific medusa we have two zones 

 of protuberances — an inner 

 zone of 16 large sacs and an 

 outer of 32 small subumbrella 

 saccules. The 16 large sacs lie 

 in the midregions of the go- 

 nads, while the 32 small sac- 

 cules lie at the zone of the 

 outer ends of the gonads. In 

 the Atlantic form the areas of 

 brown cells are commonly de- 

 veloped only centrifugal to the zone of gonad, while in the Pacific 

 variety they occur between the gonads as well as beyond them. A 

 marginal ring canal is present. The Pacific variety is, however, 

 found also in the Atlantic. 



Vast swarms of these Medusae are found among the Samoan, Fiji, 

 and Paumotos Islands, and they extend to the coasts of Africa and 

 to Queensland, Australia. They abound in Queensland in the spring 

 months, in Fiji in December, and at Singapore in April. I have 

 studied a large collection of these medusae taken in the Philippine 

 Islands at Mactan, near Cebu, on April 6, 1908, Cat. No. 27944, 

 U.S.N.M., by the United States Bureau of Fisheries steamer Alba- 

 tross. All were mature. 



Vanhoffen (1913) reported that he succeeded in demonstrating 

 that a marginal ring canal is present in the Atlantic L. unguiculata, 

 although after many tests I have been unable to detect its presence in 



B 



FIG. 6. — LlNDCHB UNGUICULATA. A, THE 

 USUAL ARRANGEMENT OP THE SUBUMBRELLA 

 WARTS IN THE TROPICAL ATLANTIC FORM. 



B, The usual arrangement of the sub- 

 umbrella WARTS IN THE PACIFIC FORM. 



G, Enlarged view of lips, gonads, and 



SUBUMBRELLA SACCULES IN THE PACIFIC 

 FORM FROM THE PHILIPPINES. 



