CHARYBDEA RASTONII. 17 



Charybdea rastonii Haacke. 



Charybdea rastonii Haacke, '87, p. 591, taf . 35 ; Mayer, : 06, p. 1134, pi. 1, figs. 1-1 c. 

 ? Charybdea arborifera Maas, '97, p. 86, taf. 14, figs. 7-10. 



Plate 1, Fig. 4; Plate 10, Figs. 1-7. 



Three specimens, Mangareva Harbor, surface. 



I have likewise had the privilege of examining the considerable series 

 from the Hawaiian Islands, including various stages in growth, on which 

 Mayer based the record noted above. 



The specimens present immature characters in the structure of the 

 phacelli and velar canals, and agree very closely with Haacke's ('87) de- 

 scription of the young of this species from near Adelaide, Australia, as well 

 as with Hawaiian specimens of a corresponding size. The measurements 

 of the present specimens are, 13 mm. in diameter by 14 mm. high; 13 mm. 

 in diameter by 13 mm. high ; 8 mm. in diameter by 9 mm. high. In the 

 largest specimen, which, from the condition of the gonads, is apparently about 

 half grown, the bell is rather cubical, and the exumbrella shows the sculp- 

 ture characteristic of the genus (PI. 10, figs. 2, 3). The pedalia, which have 

 often been considered of systematic importance in this genus, are narrow and 

 ovate in all the specimens, being but slightly deeper along their inner 

 than alone their outer sides. The stomach, as is shown in a somewhat ideal 

 section (PI. 10, fig. 6), is very flat, without any trace of the mesenteries 

 characteristic of the allied genus Tamoya. 



The canals. — In every specimen there are sixteen canals, four between 

 every two frenula, the two near the tentacles being larger and longer than 

 the two near the sense organs. In the two smaller specimens from Manga- 

 reva all the canals are simple, but in the largest individual one of them 

 shows signs of branching, thus indicating that the simple condition is merely 

 a temporary one, as Haacke ('87) has pointed out. In larger specimens, 

 Hawaiian, the branching is more complex, resembling Haacke's figures of 

 adults. 



The phacellae. — In the smallest specimen these consist of ovoid thicken- 

 ings at the four corners of the stomach, each bearing from ten to fifteen 

 simple filaments. The largest specimen shows a much more advanced con- 

 dition. The filaments in each phacella (PI. 10, fig. 7) have become collected 

 into three or four groups, each group arising Erom ;i distinct stalk. The 

 filaments, furthermore, arise from the stalk at different levels, and some of 



