RHIZOSTOM.E LOBOXKMA. 689 



with the stomach. The suhumbrella exhibits a well-developed system of entire ring muscles. 

 There are numerous prominent, tapering, nematocyst-bearing papilla; upon the exumbrella. 

 All 16 of the radial-canals extend to the bell-margin. There is a sensorv pit on the exumbrella 

 side above each rhopalium and the floor of this pit is furrowed. 



Lobonema sraithii, gen. et sp. nov. 



This species is named in honor of Dr. llui;li M. Smith, Deputy United States Fish Com- 

 missioner, who found it in Manila Bay. Philipine Islands. The Albatross found a perfect 

 specimen of this medusa, and a quadrant of its disk and all of its mouth-arms were preserved. 

 There were also two other imperfect specimens, so that all three taken together afford data for 

 a partial description of the medusa. 



Bell flatter than a hemisphere, 2 56 mm. across from each sense-club to the one 180 from it. 

 Gelatinous substance thick, tough, and rigid. Exumbrella regularly besprinkled with erect, 

 gelatinous papilla; which are largest and most abundant at the center of the exumbrella but dis- 

 appear near the margin and are not seen over the lappets. Near the center of the exumbrella 

 these papilla? are about 6 to 10 mm. apart and each is about ^5 to 40 mm. long and 3 to 5 mm. 

 wide at the base; they are conical, usually more or less curved, and taper to pointed ends. 

 Their surfaces are thickly covered with nematocysts, which give a bristling appearance to the 

 disk of the medusa. 8 rhopalia which lack ocelli in specimens preserved in formalin or alcohol. 

 On the exumbrella side above each sense-club there is a shallow, heart-shaped, senson pit 

 with dendritic ridges over its floor. The rhopalia are flanked hv very small, m al, ocular lappets 

 only 3 mm. long and 2.5 mm. wide. There are 32 (4X81 velar lappets which are most extra- 

 ordinary, each being 90 to 100 mm. long and tapering gradually from base to tip. 1 hey are 

 modified so as to resemble superficially tentacles of semaeostomous Scyphomedusje and trail 

 downward from bell-margin, waving flexibly to and fro as do \eritable tentacles; I can find no 

 muscles in these lappets, however, and do not believe that they can contract and elongate. 

 There are deep clefts in the exumbrella surface between the lappets, but these clef's are bridged 

 over by a thin subumbrella membrane spanning between the lappets. The 8 inter-rhopalar 

 grooves are 35 mm., the 8 rhopalar 16 mm. and the 16 intermediate clefts 31 mm. long. 1 he 

 8 rhopalar clefts are \ shaped and the exumbrella sensory pit is at the middle of the crotch 

 of the \ with the divided groove on either side of it i see text-figure 418, c ). 1 he grooves 

 between the velar lappets are simple, undivided, linear clefts. 



16 radial-canals, 8 rhopalar and 8 inter-rhopalar, leave the central stomach and all extend 

 to the bell-margin. There is a fairly distinct ring-canal about 30 mm. inward from the sense- 

 clubs, and this ring-canal gives rise on both its inner and outer sides to an anastomosing net- 

 work of vessels which connect with the 16 radial-canals, but not directly with the stomach. 

 This network of vessels extends downward throughout the length of the tapering lappets 

 trending mainlv longitudinally but with frequent anastomoses. 



The muscular svstem forms an armulus about 68 mm. wide in the subumbrella from the 

 margin of the arm-disk to the /.one of the rhopalia. The circular muscles are powerfully 

 developed, and are only thinned but not broken in the rhopalar radii. There are no radial 

 muscles and no muscles in the lappets. 



The arm-disk is 100 mm. wide but as it was cut off, I can make no statements in ref- 

 erence to the size or form of the subgenital ostia or of the gonads. 



The 8 mouth-arms are sepaiate, 150 mm. long, and each is 3-winged below. The upper 

 shaft of each arm is 60 mm. and the .{-winged lower part 90 mm. long. It is remarkable that 

 each of the 3 lateral membranes is perforated by 3 windows or openings (see diagram \. 

 text-figure 418). The axial duct of the arm extends down the center and gives offside branches 

 in the tissue between the windows to the mouths. These side branches are joined one to 

 another hv longitudinal canals near the frilled mouths (see text-figure 418, n). 



There are numerous appendages upon the mouth-arms arising between the mouths. 

 Those near the lower pointed ends of the mouth-arms are large, spindle-shaped, more 01 K-ss 

 triangular in cross-section and taper to pointed ends. Those arising higher up are more 

 slender, and above these there are mere thread-like filaments. The appendages are usuallv 

 70 to 100 mm. long, and the large ones contain an axial duct. The general color of the medusa 

 in formalin is milky-gray. The mouths and gonads being darker than other parts. 



