LIMNOCODIUM IN THE UNITED STATES. 3 I I 



cysts, according to these observers. But I have failed to find 

 any well defined cases of such highly specialized nematophoric 

 structures. The figures, both from the drawings and the photo- 

 graph alike, confirm this statement. I cannot resist the impres- 

 sion that the figures of the former must have been drawn from 

 greatly distorted specimens due in part perhaps to mode of pres- 

 ervation, or that they may have been made from very young 

 tentacles in which the nematocysts are relatively more conspicuous. 

 A comparison of various of my specimens fails to reveal any es- 

 sential differences, even where various modes of preservation were 

 employed. An examination of the specimen represented in Fig. 

 7 will show fairly well the general distribution of the nemato- 

 cysts, and also the tendency to an annular disposition similar to 

 that common to other hydromedusae. 



Marginal Bodies and Velar Canals. 



Concerning these organs I have made no attempt to critically 

 investigate anew their structure or development, beyond a more 

 or less careful review of the work of Lankester, and the later 

 work of Giinther {op. cit.). So far as I have gone my observa- 

 tions confirm that of the previous investigators. Fig. 5 is a 

 camera sketch of a portion of the margin and velum showing the 

 general aspects of the several organs, tentacles, marginal bodies 

 and capsules, and velar canals. But while confirming the facts 

 described by Lankester as to the structure and relations of the 

 marginal bodies, I have found no convincing evidence of his rather 

 dogmatic assertion that " The refringent body is nothing more 

 nor less than a modified tentacle." This may have sufficed its 

 author at the time it was made, and was quite in harmony with 

 then current views concerning these organs in general. But the 

 time has long since passed when the mere matter of similarity of 

 structures, real or imaginary, is any sufficient warrant for the 

 vaulting conclusion involved in the above quotation. In another 

 connection (Jour. Exp. Zo'dl., Vol. I., p. 86), I have taken occasion 

 to question the long current assumption that in Scyphozoa the 

 rhopalia are metamorphosed tentacles. Later observations have 

 only served to deepen the conviction, and I believe adequate 

 investigation will confirm the view that these organs are not, in 



