52 ART. 7. 1. IJIMA : IIEXACTINELLIDA, IV. 



in ])art, arranged in reticular tracts in the same way as those in 

 the oklest larva I have seen of Leucopsacus ovthodocus (Contrib. 

 III., p. 46 ; PL III., fig. 25), the cellular tracts occupying the 

 same space as the trabecular reticulum with wliicb they are 

 joined together. 



As to the })robable origin of the cliaml)ers (hiring the meta- 

 morphosis, I can here do no more tlian refer tlie reader to the 

 considerations I have laid down on p. 1(>J of my Contribu- 

 tion I. 



iSTow as to the s[)icnles of the larva. As before stated, they 

 lie mainly in the pei'iphery of the inner mass, — close under, but 

 ]iot in direct contact with, the external e])ithelium. As in the 

 larva of Leucopsacus orlhodocus, they are all stauractins {cfi\ pp. 

 44-46, Contrib. III.). They are always so oriented in relation 

 to the form of the larva that we may sj)eak of the transverse 

 and the longitudinal axes (PI. III., fig. 20). The former is al- 

 ways the shorter, and the two rays in it are usually of about 

 e(pral length. Of those forming the longitudinal axis, one is as 

 a rule much longer than the other. The four I'avs are in a 

 ])lane more or less concave on the inner side, in conformity with 

 the curvature of tbe Ijody-surfiice. In the manner of distribu- 

 tion of the spicrdes, a strict regularity is Jiot observable beyond 

 the fact that the centers lie well separate from one another, the 

 result being that the rays run singly without coming together 

 into bundles. They ai'c of such a length that intersection is of 

 l're(|uent occuiTcnce ; there is thus brought about a latticework, 

 the meshes of which may l)e said on the whole to be rectangular 

 ))ut not regular in shape. Towards each pole of the larva, a 

 munber of longitudinally running rays converge and there come 



