HYDROMEDUSAE, SIPHONOPHORES, AND CTENOPHORES. 295 

 PHIALUCIUM MBENGHA (Agassiz and Mayer) Maas. 



Mitrocoma mbengha Agassiz and Mayek, 1899, p. 168, pi. 8, figs. 24, 25. 



Oceania virens Bigelow, 1904, p. 252, pi. 1, figs. 3, 4. 



Phialucium virens Maas, 1905, p. 32, pi. 4, figs. 36, 37 ; 1906, p. 93.— Bigelow, 



1909a, p. 157.— Mayer, 1910, p. 276. 

 Phialucium mbengha Maas, 1905, p. 32. — Mayer, 1910, p. 276. — Vanhoffen, 



1911, p. 225. 

 IPhialidium species? Hartlaub, 1909, p. 455, pi. 20, figs. 8-10 [=18-20]. 



This species has been described in detail by Maas (1905). 



The typical form of P. mbengha is represented in the collection 

 by 2 specimens, respectively, 10 (Cat. No. 29374, U.S.N.M.), and 15 

 mm. (Cat. No. 1689, M.C.Z.) in diameter, from Manila Bay, Jan. 5, 

 1909. 



In the smaller specimen the arrangement of marginal organs, as 

 shown by the graphic method of Vanhoffen (1911), is as follows: 



Tentacles, series 1 I II III IV Totals, 4. 



Tentacles scries 2 4 5 4 3 16 



Rudimentary tentacles .'!"!!!!""!. ........ 2,2,3,6,2 3,2,1,3,3,0 3,3,3,4,4 3,4,4,? 55± 



Otocysts 2,2,3,3,1 3,1,1,2,1,4 1,2,2,2,1 3,1,2,1 38 



In the larger specimen the numbers in the only quadrant which is 

 still preserved intact are : 



Tentacles, series 1 I II Totals, 2. 



Tentacles, series 2 



Rudimentary tentacles. 

 Otocysts 



6 

 5,4,6,4,3,4,6 

 2,2,3,0,2,2,2 



These tables show how very variable the number of marginal 

 organs is. Indeed, no two quadrants of either the Philippine or the 

 Valdwia specimens are precisely alike. With growth the increase in 

 number of bulbs far outstrips the increase of large tentacles. 



I have noted above the variation observed in the number of otoliths 

 to each otocyst. 



Color. — In the preserved specimens the gonads, manubrium, and 

 tentacular bases are yellowish ; in living specimens from the Maldives 

 they were pale green; in the Valdivia specimens these regions were 

 light red. 



The localities from which P. mbengha has previously been recorded 

 are Fiji, the Maldive Islands, Amboina, Ceram, Ternate, and other 

 localities in the Malay Archipelago, the Indian Ocean north of 

 Sumatra, and possibly the Gulf of Aden (Hartlaub, 1909). Its oc- 

 currence in the Philippines was therefore to be expected. 



