Boone, Coelenterata, Cruises of "Ara" and "Alva" 53 



Nagasaki, Japan. Vanhoffen reported it from the Sulu Seas and 

 Java. 



Material examined: One specimen from Banka Straits, 

 diameter about 8 inches. Two specimens from Muntok, Banka 

 Island, the complete one having a diameter of 18 inches, while the 

 much larger, imperfect specimen indicates a diameter of about 

 22.5 inches. 



Technical description: The "Alva" specimens are much 

 the largest recorded to date of this magnificent species of the 

 Rhizostomata triptera, which are distinguished from the six other 

 groups of Rhizostomae by having each mouth-arm three-winged, 

 possessing a ventral and two dorsal branches which meet at the 

 lower or free end of the arai. 



Haeckel's type measured 60 millimeters width diameter and 

 20 millimeters thick. Goette's specimens varied from 5 to 65 

 millimeters wide. 



The entire Muntok specimen has the bell wide, circular, less 

 elevated than a hemisphere, 200 millimeters diameter, about 50 

 millimeters thick near the center, about 30 millimeters thick mid- 

 way the radius and about 5 millimeters thick near the circum- 

 ference. 



The bell is about 200 millimeters wide diameter, less elevated 

 than a hemisphere and but little convex. The exumbrella is cov- 

 ered with a network of anastomosing reticulations defining irregu- 

 lar polygonal elevations. This network is coarser at the center 

 and finer meshed toward the circumference. It is probable that 

 in the present specimens these are accentuated by death. The gela- 

 tinous substance of the bell is semi-opaque, about 40 to 50 milli- 

 meters thick near the center, about 30 millimeters midway and 

 about 5 millimeters thick near the margin. It has a brownish- 

 yellowish tinge which may be due to the presence of algae. There 

 are eight rhopalia set within very shallow niches in the bell 

 margin. The velar lappets said to vary from four-double to twelve 

 per octant are eight in the present specimen, each being shaped 

 as shown in plate and separated by short, narrow clefts. The 

 arm-disk is nearly two-thirds as wide as the bell radius. The 

 four subgenital ostia are about twice as wide as the perradial 

 columns between them. The subgenital cavity is narrow, cruci- 

 form, unitary. The eight mouth-arms are each about equal in 



