170 



This species was found in the Gulf of Panama, at the Island of Taboga, 



in December 1915, a dozen specimens. 



Evidently it stands more apart from the other species and possibly does 



not really belong to the same type; still I have thought it preferable to 



include it under the 

 type of 0. piisilhis, 

 to which it bears in 

 several regards a 

 close resemblance. 

 It is impossible 

 to have any opinion 

 of the relationship 

 of this larval type. 

 That it occurs both 

 at Panama, Japan 

 and in the Indian 

 Ocean is by no 

 means a sufficient 

 foundation for any 

 suggestion as to this 

 point. Too many 

 Ophiurid genera are 

 common to the 



Fie. 94. Skeleton of Ophioplukus pusilliis, species d. -»"/i. t^ .r. ^ r 



Pacific coast of 

 America and the Indo-Pacific region to allow any such conclusions at 

 our present stage of knowledge. 



Ophiopluteus diegensis nova forma. 



PI. XXIX, Vig,. (). 



In its general ai)|)oarance this small larva (0.27 mm body lenglli) very 

 much resembles Ophiophileus piisillus. The posterolateral arms are scarcely 

 longer than the body, and the point of the anterolateral arms is at about 

 the level of that of the former ones, while the postoral and posterodorsal 

 arms remain very short. The frontal area is quite low. The posterolateral 

 rods are set with short thorns along both the outer and the inner side, 

 and the anterolateral rods have rather long thorns along their outer side, 

 as in pusillus. The postoral rods are strongly curved, with few, small thorns. 

 The body skeleton is simple; there is generally a small tliorn (in the outer 

 side near the base of the body rod. The end rods are straight, with a small 

 branch close to the point. The transverse rods have the same structure 



