199 



Species b, the Japanese form, difTers from the Atlantic first in its much 

 larger size, reaching 15 mm, the la Her not being known to surpass a length 

 of 6 mm, the stage of development being the same in both. Further I find 

 on a comparison of some specimens, kindly sent me by Dr. Ohshima, 

 with those of species a, that the body is distinctly narrower in species b 

 than in species a, and also the projecting lobes of the vibratile band are 

 larger and more prominent in the .Japanese species. Through this strong 

 development of the vibratile band, in fact, the sides of the larva are wider 

 than its dorsal and ventral sides, and the preserved specimens therefore 

 generally lie on the side, while specimens of species a generally lie on the 

 dorsal or ventral side. Whether the small diflerence in the structure of 

 the calcareous deposits pointed out by Ohshima — viz. that the edge 

 is finely serrated in the Japanese specimens, while Chun states it to be 

 smooth in the Atlantic species — is a reliable difference needs lo be verified 

 by a reexamination of the latter; I am sorry to be unable lo settle this 

 question, all my specimens having been preserved in formaline, and the 

 deposits thus having been dissolved. 



Species c, the New Zealand form, is likewise considerably larger than 

 species a, the single specimen known measuring '"at least a centimetre in 

 length". Otherwise it is impossible to state by which other characters it 

 is distinguished from species a and b, no description or figures having been 

 given of it. Only in one feature it is stated lo differ from the two other 

 species, viz. in the median ventral pouch from the intestine being paired, 

 while in the two other species it is unpaired. It would appear from the 

 expression used by MacBride (Op. cit. p. 89), running thus: "This single 

 diverticulum is supposed to be a rudimentary representative of the gill- 

 (lung-)trees of other flolothurioidea; but the discovery that the pouch is 

 paired deprives this argument of its ground", that he thinks C h u n " s state- 

 ment of the pouch being unpaired in the Atlantic form lo be wrong. I 

 would then lake the opportunity of confirming Chun's statement. There 

 is not the slightest doubt that the pouch is really unpaired, as figured by 

 Chun, and the same is the case in the Japanese species. 



On account of this intestinal pouch Chun was inclined to refer this 

 larva to some Elasipod, and I have joined him in this opinion. MacBride, 

 however, thinks this a mistake. Having found in a species of Cuciimaria 

 the gill-trees to appear only in a rather advanced stage of development, 

 he finds it 'exceedingly unlikely thai a rudiment of these gills should 

 appear in the Aiiricularia larva*; they probably only begin to develop when 

 the cloacal function of sucking in and ejecting water has been established. 

 I conclude, therefore, thai the intestinal pouches of A. onlarctica and .1. 



