157 



in the type. The spinulation, of course, varies with the size of the pro- 

 cesses. Some specimens observed aUve at Misaki, Japan, in June 1914, 

 were found to have the stomach green, while some tiny red pigment grains 

 were scattered along the body skeleton. No pigment spots in the tip of 

 the arms. 



Numerous specimens were found from Japan to the Red Sea: Misaki, 

 Japan, 29/IV, 2-17/VI. 1914; Zamboanga, l/III. 1914; Malacca Strait, 



Fig. 84. Skeleton of Ophiopluteus serratus. ^''/i- Letters as in fig. 61. 



30/XI. 1899; S. of Koh Chuen, Gulf of Siam, 3/III. 1900; 89n5' E. 5° 55' N. 

 (Bay of Bengal), 5/1. 1914 (1 specimen); 73° 34' E. 7° 37' N. 26/IV. 1900 

 (1 specimen); Gulf of Aden, 14/XI. 1899; Strait of Bab-el-Mandeb, 5/V. 

 1900 (1 specimen); of! Jebel Zukur, Red Sea, 5/V. 1900; Suez, 31/1. 1898 

 (Mr. H. Mortensen). 



A very interesting feature is connected with the metamorphosis of this 

 larval type. The suboral cavity continues some way down in the body, as a 

 pouch on each side of the stomach. In the wall along the bottom of this 

 pouch a thickening appears at the time, when the hydrocoel begins to 

 form lobes (PI. XXVIII, Fig. 2); this thickening grows very considerably 

 and forms lobes, which ultimately combine with the lobes of the hydrocoel. 



