168 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
with large basal bulbs. Sixteen otocysts, each containing a single spherical - 
otolith, alternate with the 16 marginal tentacles. The velum is well devel- 
oped. There are 4 straight, narrow, radial canals, upon the lower region of 
which, near the circular canal, the gonads are developed. In the female the 
ova are very large and prominent. The proboscis is small and flask-shaped, 
and there are 4 curved lips. The entoderm of the proboscis, tentacle bulbs, 
and radial canals in the region of the gonads is green. 
Several specimens found in Suva Harbor early in January, 
Tiaropsis rosea, nov. sp. 
Plate 7, Figs. 21, 22. 
Generic Characters. Tiaropsis, L. Agassiz, 1849. Eucopide with 8 otocysts 
and 8 pigment spots (2 in each quadrant). There are numerous otoliths within 
each otocyst. The gonads are developed upon the 4 radial canals. There is 
no peduncle to the proboscis. . 
Specific Characters: Young Medusa. The hell in the young Medusa ob- 
served by us was ellipsoidal in shape, and 2.6 mm. in height. There were 4 
well developed marginal tentacles that were coiled in a close helix. The bulbs 
of these tentacles were large. In addition to the tentacles mentioned above, 
there were 4 small protuberances upon the bell margin that probably repre- 
sented the beginnings of other tentacles. ‘There were 8 marginal sense organs 
(Figs. 21, 22), 2 in each quadrant. These consisted (Fig. 22) of an entodermal 
pigment spot, and a number of otoliths contained in an open fold of the velum, 
A cross section (Fig. 23) of the sense organ of Tiaropsis diademata, L. Agassiz, 
will serve to illustrate their structure. In Figure 23 the entoderm is repre- 
sented in brown and the ectoderm in gray; the section is taken through the 
bell margin. It will be seen that the pigment spot ( pq.) is situated within the 
entoderm upon the inner side of the circular tube (cf.); and that the otoliths 
(ot.) are ectodermal and enclosed within an open fold of the velum (vel.). 
There were 4 straight broad, radial tubes. The proboscis was small, and 
there were 4 prominent, fimbriated lips. The gonads had not yet made their 
appearance. A number of immature specimens were found in Suva Harbor 
early in January. 
A species that is closely allied, if not identical, with this Medusa is found at 
the Dry Tortugas Islands, Florida. 
Mitrocoma mbengha, nov. sp. 
Plate 8, Figs. 24, 25. 
Generic Characters. Mitrocoma, Haeckel, 1864. Eucopidee with numerous 
open otocysts, and numerous tentacles and cirri. Gonads upon the 4 radial 
canals, No peduncle to the proboscis. 
