6 UNIVERSITY OF MISSOURI STUDIES [l94- 



tenna-like structures may be subdivided into two classes : in the 

 first a flagellum arises from the distal end of a larger basal por- 

 tion which resembles the horn-like process of the first type ; and 

 in the second a flagellum proceeds, not from the distal end of 

 the basal horn-like portion, but from its side, thus forming a 

 forked structure borne on a common base. The flagellum is 

 not beset with long hairs as in the shorter process, but on the 

 distal borders of the segments are tufts of setae similar to the 

 setae found on the flagella of the antennules. Presence or ab- 

 scence of light had no apparent effect upon the character of 

 regeneration, although a much larger percentage of the indi- 

 viduals kept in the dark than of those kept in the light showed 

 regenerative power. 



Sicyonia sculpta ('96), a member of the same family as 

 Palaemon, furnished material for the second series of exper- 

 iments. These were also confined to the total excision of the 

 eye, and the observations are recorded with much greater pre- 

 cision in this case than in the first. Most of the animals oper- 

 ated upon were about four and a half centimetres in length. 

 The mortality resulting from the operation was not as great 

 as in the cast of Palaemon, but the animals were very much 

 harder to feed, and often refused food for days at a time. They 

 were, consequently, less favorable for experiment, and of 85 

 individuals operated upon during the latter part of October, on 

 the sixteenth of the following April only 6 were living. No 

 signs of regeneration were apparent before the last of January, 

 even though a moult had taken place. Two, three, or perhaps 

 four moults were found to be necessary before any definite 

 structure appeared. Among those that lived until April, only one 

 showed no regeneration whatever. The structures regenerated 

 by Sicyonia resembled closely those already described for Palae- 

 mon. However, in the case of Sicyonia, Herbst comes to the 

 conclusion that the antenna-like organs resemble the antennules, 

 first antennae, more nearly than the second antennae. 



