﻿ix. d, 3 Light: Some Philippine S-cyphomedusx 209 



to twice as wide as the interostial pillars. The genital porticus 

 is unitary and cruciform. The circular muscles extend uninter- 

 rupted from the outer end of the arm disk to the margin. 



The arms are 6 mm. long. Each has a swollen area near 

 the base, culminating on the outside in a laterally projecting 

 point beyond which the arms are decidedly narrowed. The 

 mouths are on the lower and inner surfaces of the three branched 

 arms. 



In life, the medusa is deep, rich plum ; in formalin, it is pur- 

 plish brown. 



This immature form was collected from a seine at Pasay 

 Beach, Manila Bay, October, 1913. It is particularly interesting, 

 because of the presence under the edge of the margin of several 

 small cyclopslike Crustacea, evidently leading a commensal 

 existence. Four of these crustaceans were found, each lying 

 just below a sense organ and along the line of a rhopalar 

 canal, the head end lying innermost. They were all females 

 with well-developed egg sacks, and were difficult to make out 

 in position as they have many minute brown pigment spots 

 scattered over the body, giving them the same general color 

 as the medusa. 



I have since found that these Crustacea are to be found in 

 great numbers on living specimens whether mature or immature 

 and are not confined to any one region of the medusa. 



Genus MASTIGIAS L. Agassiz, 1862 



Mastigias papua L. Agassiz. 



There are 3 immature and 2 mature specimens of this medusa 

 in the collection from Port Galera Bay, Mindoro, collected during 

 May and June, 1912. I saw many small specimens in Taytay 

 Bay, Palawan, in May, 1913. 



These forms differ somewhat from the typical M. papua, and 

 while these differences coincide to some extent with those noted 

 in M. papua var. sibogse Maas they differ to about the same 

 extent. They seem to be intermediate in form between M. papua 

 var. sibogse and M. papua forma typica, and the specimens differ 

 among themselves as to coloration, length of filaments, etc. 

 These facts lead me to believe, as Mayer says, that there are 

 numerous very closely related or even intergrading forms in 

 this genus. It would be interesting to compare large series of 

 these medusa? from localities joining two rather widely separated 

 habitats, say Japan and Papua, getting series from Japan, 

 Formosa, Luzon, Mindanao, Jolo, Amboina, and Papua. I have 

 no doubt that the individuals of such a series would so inter- 



