558 MKDUS.E OF THE WORLD. 



There are, I believe, but two species, L. iingiitculata of the tropical Atlantic and /.. aquila 

 of the Pacific and Indian Oceans. These are closely related, but in the Atlantic form 

 there is no marginal ring-canal, whereas this is present in the Pacific species; moreover, the 

 subumbrella warts of the Pacific form are arranged in 2 rows and in the Atlantic medusa in 

 3 rows. 



Linuche unguiculata Eschscholtz. 

 Plate 59, figs. I to lo. 



Medusa unguiculata, Schwartz, 178S, Neuc Abhandl. Schwcil. Acad. Deutsche Ucbers., 1789, p. 195, tat. 6, fig. i.— LinnJ 



(Gm£Un), 1788, Syst. Nature, tomus 1, pas. 6, p. 3159. 

 Pelagla unguiculata, PtRON et Lkssukr, 1809, .Annal dii Museum Hist. Nat., Paris, tome 14, p. 549. 

 Linuche uni-uiculata, Eschscholtz, 1839, Syst. der Acal., p. 91 .— Blainville, 1834-1836, Manuel d' Actinologie, p. 289, planche 



37, figs. i-ic. 

 Linerges mercurius-^L. pegaius+ Liniscus OTitithopterus (?) -f L. tandalopterut (?) 4-L. cyanwpterus-\- Linuche unguiculata + 



L. vesiculata, Hakckel, E., 1880, Syst. der Meifusen, pp. 495, 497, 498, 499, taf. 29, fign. 4-6. 

 Linerges mercurim, Fewkes, 1882, Bull. Mus. Comp. Zool. at Harvard College, vol. 9, p. 259, plate 2, figs. 3-5; plate 3, figs. 4-8, 



II, 13; plate 4, figs. 3-22; 1886, Report Commiss. Fish and Fisheries for 18S4, p. 950. — Ar.Assiz, A., 1888, Bull. Mus. 



Comp. Zool. at Harvard College, vol. 14, p. i85, fig. 93. — Mayer, 1900, Bull. Mus. Comp. Zool. at Harvard College, vol. 



37, p. 68. — CoNKLiN, 1906, Year Book of Carnegie Institution of Washington, No. 4, p. 115; 1908, Papers from Tortugas 



Laboratory Carnegie Institution of Washington, vol. 2, p. 153, 8 plates (development). 



Bell about 13 mm. high and 16 mm. wide. Lenticular apex flat and horizontal, separated 

 from the vertical sides by a distinct but shallow annular furrow. Occasionally a few irregu- 

 larly arranged, radiating clefts are found in the margin of the lenticular apex of the bell, 

 but this is usually plain. Sides of bell composed ot 16 vertical pedaiia, similar each to each, 

 and separated one from another b\' 16 clefts in the radii ol the mid-axial lines ot the lappets. 

 Thus the pedaiia are in the radii of the tentacles and rhopalia and alternate with the lappets 

 (plate 59, fig. 2). 



The 16 lappets are bluntly oval with rounded edges and are all inclined inward at an 

 angle such that when one observes the medusa by looking down upon the aboral end of the 

 bell the animal rotates with the hands ot the watch as it swmis through the water, upon each 

 contraction of its margin. The lappets being inclined as are the vanes of a wind-mill cause 

 this peculiar spinning on its axis as the medusa progresses rapidly along. This was discovered 

 b^" Prof. E. G. Conklin in 1905. 8 small, simple, marginal sense-organs, perradial and inter- 

 radial in position, arise from clefts between the lappets and are not protected by covering 

 scales. The entoderm of each rhopalium contains a spherical mass of concretions. No 

 ocelli. The 8 adradial tentacles are small, neither very flexible nor contractile, and only 

 about 1.5 times as long as lappets. 



The 8 (4 double) gonads form 4 cleft crescents on both sides of the perradial lines of 

 the subumbrella, the cleft being in the perradius itself and the horns of the crescents extending 

 outward toward the margin of the bell. These gonads begin to develop as 8 separate sacs 

 diverging outwardly on either side of the 4 perradii when the ephyra is about 5 mm. in diameter. 

 The subumbrella sacs are not male gonads as was conjectured by Haeckel, and the medusa 

 is not hermaphroditic, the sexes being separate. 



The proboscis is urn-shaped, 4-sided, and with 4 slightly recurved lips with their perradial 

 angles truncated so as to present a nearly octangular appearance when \icwcd upon looking 

 into the bell-cavity. The mouth does not extend to level of bell-margin, but is usually at 

 about two-thirds the distance down from the inner apex of the bell-cavity. There are 4 cres- 

 centic interradial rows of simple unbranched gastric cirri, about 15 to 20 in each row at the 

 interradial septal nodes. Beyond these, and connected with the central stomach by 4 perradial 

 ostia.is the broad bell-sinus, which in turn gives rise to 16 radiating pouches in the radii of the 

 sense-organs and tentacles. Vht edges of these pouches break up mto numerous, ragged-edged 

 branches in the lappets, but I am unable to find any marginal ring-canal, for although I have 

 often injected the lappet-pouches with air, carmine, or other stains, each pouch is evidently 

 completely separated from the two adjacent to it. This appears the more remarkable from 

 the fact that Maas has found a marginal ring-canal in the Pacific species; a tact which I am 

 enabled to confirm in specimens Irom the Philippine Islands, and Claus, Vanhoflen and Bige- 

 low have demonstrated that such a structure exists in other Eph\ropsida?. 



Projecting from the floor of the subumbrella into the bell-cavit\- arc 48 hollow sac-like 

 or wart-shaped protuberances which arise from the radial stomach-pouches and are arranged 



