224. BULLETIN OF THE 
HYDROIDA. 
Sarsia mirabilis, Ac. 
Many specimens of Sarsia were seen at Grand Manan on a single excursion. 
Later they disappeared, and were not again collected. The hydroid Coryne * 
was also found. 
Hydrichthys mirus, gen. et sp. nov. 
Plates IV., V. 
During the month of August of the past summer (1887), in the surface 
fishing carried on at the Newport Marine Laboratory, I captured a most inter- 
esting genus of parasitic hydroid. This genus and its peculiar life are un- 
described as far as known. The mode of parasitic life is most extraordinary, 
and the modification of its structure of an anomalous character, 
A small fish of the genus Seriola (S. zonata, Cuv.) was taken in the dip- 
net at a time when the sea was quiet.{ Upon the side of the body (Plate IV. 
primitive medusa, the ancestral form of the medusz, with the prototype (“ Pili- 
dium-like larva ’’) of the six groups of marine larve described by Balfour. It is 
thought that such a resemblance not only exists, but also has an important phylo- 
genetic meaning. It is not in place to discuss this question in this paper. 
It may be asked whether the primitive larva of Agalma, with its huge primitive 
covering scale, or the primitive larva of Nanomia, where that scale is replaced by 
a float, is nearest the primary or ancestral larva of Hydromeduse. The youngest 
forms of the primitive covering scale and the float closely resemble each other, 
and the departure from that form seems greater in Agalma than in Nanomia. A 
nectocalyx seems more highly organized than a pneumatophore ; still, between a 
primitive hydrophyllium, such as exists in Agalma, and a float like that of Nano- 
mia, it is hard to tell which is more highly specialized. It cannot be said that the 
adult Nanomia is less highly specialized than the adult Agalma. Although the float 
of Nanomia is first formed, it follows the primitive hydrophyllium in Agalma. — 
While this fact might seem to indicate want of homology of the float in the adults 
of the two genera, it does not seem to prevent our considering the primitive larva 
to be represented by the young Nanomia with a float and no covering scale. 
* Although it was not my intention to speak of the hydroids collected in the 
Bay of Fundy, I must mention beautiful specimens of Corymorpha dredged in 
shallow water not far from Eastport. The meduse were just ready to drop from 
the hydroids, and as they were almost mature in July probably in later months 
they are found in abundance free swimming in the sea. I was of course on the 
look-out for the so-called free hydroid Acaulis, Stimpson, and other similar hy- 
droids, but was unable to collect any of these animals. The broken heads of the 
hydroid Pennaria, which somewhat resemble Acaulis, were found. 
+ The Seriola was in company with two others. Neither of its companions, 
however, were afflicted with the parasites mentioned below. 
