AGASSIZ AND WOODWORTH: VARIATIONS IN EUCOPE. 123 
In the increase and special arrangement of the otoliths in the sense 
organ of Eucope we find the first trace of the specialization of the sense 
organs of such genera as Oceania, Tiaropsis, and the like. 
There were no variations noted in the shape of the digestive cavity, 
or in the number of actinal lobes of the manubrium, even in specimens 
with five or six radial canals in place of the normal number (four) o 
radial canals. The actinal folds were always found to be four in number. 
In one case only have we found the radiating canal originating from the 
eircular canal. (Plate VIII. Fig. 19.) 
The origin of the peculiar club-shaped intertentacular appendages 
characteristic of Halopsis and Laodicea, as well as the spur at the base 
of the tentacles in many Æquoridæ, may be referred to the spur-like 
appendages of the marginal tentacles of. Eucope figured in Plate VIII. 
Figs. 4-13. 
And it may not be far out of the way to look upon the coalescence 
of adjoining marginal tentacles with sense organs as the first indication 
of such structural features as the radial marginal tentacles of Eucheilota, 
or even of Boungainvillia, Margelis, or Nemopsis. 
It is interesting to note that in Echinoderms there are five radial canals, 
and four or six or more are considered monstrosities, while in Acalephs 
four or its multiples are the normal number of radial canals, and five or 
less are variations. 
'The specimens of Eucope showing numerical or structural variations 
were as a rule fully developed males or females, the eggs and sperma- 
tozoa being apparently in a healthy condition. 
It would be an interesting study in heredity were it possible to breed 
the variations in Eucope here enumerated, and ascertain how far the 
structural characters acquired in the variations we have observed can be 
transmitted, and lead perhaps finally to the formation of types which 
we have been accustomed to look upon as having no structural relation 
with the genus. 
But it is also possible that in a comparatively simple genus like 
Eucope these variations are not necessarily to be considered as heredi- 
tary; they may indicate possibilities in. mechanical combinations which 
1 Variations in the manubrium have been observed in Tubularian Hydroids, such 
as Lizzia, Dysmorphosa, Hybocodon, Dipurena, and Sarsia ; but as they are usually 
connected with phenomena of reproduction and of budding they have only a dis- 
tant connection with the line of the present investigation. See an interesting 
paper by Hartlaub on the reproduction of the manubrium of Sarsia, in Verhandl. 
d. Deutschen Zool. Gesell., 1890. 
