Medusae of the Philippines and of Torres Straits. 175 



medusae taken in the Philippine Islands at Mactan, near Cebu, on April 6, 

 1908, by the United States Bureau of Fisheries steamer Albatross. 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 was unable to detect its presence and am inclined to believe that 

 the delicate membrane separating adjacent pouches was broken in Vanhoffen's 

 specimens, which were preserved in formalin. Moreover, Vanhoffen found 

 that in some of the Atlantic medusae from the Bahama-Florida region the 

 subumbrella warts are arranged as in L. aquila of the Pacific. It thus appears 

 that the Pacific form is at best only a variety of the Atlantic species, and both 

 should be called Linuche unguiculata. 



Genus ATOLLA Haeckel, 1880 sensu Fewkes. 



Atolla, HAECKEL, 1880, Syst. der Medusen, p. 488. FEWKES, 1886, Report Commissioner of 

 Fish and Fisheries of U. S. for 1884, p. 934. MAYER, 1910, Medusae of the World, vol. 3, 

 p. 561. BROWNE, 1910, National Antarctic Expedition, Nat. Hist., vol. 5, Ccelenterata, 

 V, Medusae, p. 47. 



GENERIC CHARACTERS. 



Coronatse with numerous (9 or more) tentacles and equally numerous 

 marginal sense-organs. Twice as many marginal lappets as sense-organs. 8 

 adradial gonads and 4 interradial subgenital ostia. 4 lips. The tentacles and 

 marginal sense-organs alternate regularly, but the insertions of the tentacles 

 and their pedalia are higher up on the sides of the exumbrella than are the 

 insertions of the pedalia of the sense-organs. 



The Albatross collection serves to show that A. wyvillei and A. bairdii are 

 closely related if not mere extremes of an intergrading series of one and the 

 same species. For example, two specimens from station D 5652 in the Gulf 

 of Boni, depth of 525 fathoms, have the margin of the central lens distinctly 

 notched with radial furrows as in the typical A. wyvillei; but there is an 

 annular ridge on the outer side of the ring-furrow with a plain peripheral 

 margin as in A. bairdii. Also several other specimens show such very slight 

 notches in the margin of the central lens that if one were not looking carefully 

 for this feature it would surely pass unobserved and the medusa would be 

 called A. alexandri. A large specimen of A. gigantea, from a depth of 519 

 fathoms in Buton Strait, shows affinities with A. wyvillei, A. bairdii, and A. 

 verrillii. Thus the margin of its central lens is irregularly notched as in A. 

 wyvillei, but without radial furrows. There is an annular ridge upon the 

 outer side of the ring-furrow, and the outer edge of this ridge is simple and 

 entire, as in A. bairdii, in about two-thirds of its circumference, and notched 

 as in the typical A. gigantea in the remaining one-third. The central lens is 

 more than half as wide as the medusa, as in A. bairdii, A. verrillii, and A. 



valdivice. 



It is evident that intergrading conditions prevail to a hopeless degree among 

 many of the so-called "species" of Atolla. In fact, I think there are but two 

 well-distinguished species: A. bairdii with smooth exumbrella and A. chuni 

 with well-developed and quite regularly arranged papillae upon the exumbrella 

 sides of the lappets. As a matter of convenience, however, we may distinguish 

 A. bairdii var. wyvillei by the notched margin of its central lens, and the 

 absence of a well-marked annular ridge on the outer side of its coronal furrow; 

 for while there is often an annular ridge on the outer side of the ring furrow, 

 the margin of the central lens usually projects over it, overarching and con- 

 cealing it from view. A . bairdii is a case where this ridge is so well developed 

 that it projects beyond the margin of the central lens. 



