MUSEUM OF COMPARATIVE ZOOLOGY. 221 
The egg of Nanomia in the eight-cell stage is the oldest which has been 
studied. There seems to be nothing peculiar in the method of segmentation 
as compared with that of Agalma. Among other meduse it has some like- 
nesses with that of the Ctenophora and certain Trachymeduse. 
Between the eight-cell stage and the youngest as figured by A. Agassiz 
there is a considerable gap, which I am not able to fill by new observations. 
This interval is, however, in part bridged by observations on an allied genus 
found in the Mediterranean, already published by Metschnikoff. This ob- 
server * has studied a Siphonophore, which is closely allied to Nanomia, and 
seems to resemble in mode of growth, as far as known, that which has been 
already described and figured by A. Agassiz. 
Older larve, which he supposes to belong to the same genus, Metschnikoff 
has raised from planulze which are a little younger than the youngest Nano- 
mia figured by A. Agassiz. He has shown that in these larve no “ primitive 
hydrophyllinm” + is formed, and that the first structure to develop is the 
float. He regards his genus as the same as Nanomia. 
A few years ago I was inclined to regard the genus referred to by Metschni- 
koff as the same as Nanomia. The adult tentacular knobs described for the 
first time in this paper confirm me in that opinion, but there is one thing 
which leads me to doubt their identity. The existence of the large oil glob- 
ules in the bases of the tasters is very exceptional among Physophores. I 
have studied the animal, Stephanomia pictum, referred to by Metschnikoff, 
and was one of the first to describe it,f but I do not remember seeing struc- 
tures similar to the ‘oil globules” of the tasters of Nanomia. In the 
published descriptions of this animal there are no similar structures. The 
question then arises whether the presence of this structure is sufficient to sep- 
* Op. cit. e 
t+ The term “ primitive hydrophyllium” was suggested in my paper on the 
development of Agalma to designate the cap-shaped covering scale which forms 
such an important organ in determining the form of the larva. The designation 
“primitive larva,” used to distinguish the stage in which this organ is most de- 
veloped, was suggested in the same paper. The primitive larva is supposed to 
be an ancestral form of Calycophores and Physophores, and to be closely allied 
to the ancestral form of other Hydromeduse. 
+ Contributions to a Knowledge of the Tubular Jelly-fishes, Bull. Mus. Comp. 
Zool., Vol. VI. No. 7, pp. 156, 137, Plate II. Neither in Metschnikoff’s figure of 
Stephanomia, nor in Claus’s figure of Halistemma tergestinum, which all seem to re- 
gard the same, the relative size of the hydrophyllia seems to be smaller than in 
Nanomia. The same is true of my Agalmopsis from Florida. Claus’s figure of the 
taster of his Halistemma, Plate II. Fig. 4, shows what may be a small “oil glob- 
ule” near the base of this organ, and the structure in the same figure lettered mq, 
“male sexual bell,” has some resemblance to the “oil globule” of Nanomia. 
Still from his description it does not seem that the “oil globule” has the predom- 
inance in size which it has in Nanomia. It must also be said that if mg (Plate II. 
Fig. 4) is a male sexual bell, it is very different from the same bodies in Nanomia. 
