REPORT ON THE PTEROPODA. 
95 
If we restrict our attention to Cymbulia peroni and Gleba cordata, the question 
s indeed simplified. We see then, in Gleba , a free elongated proboscis, a fin with 
ontinuous margin, without ventral lobe, and a “ shell ” of considerable delicacy, almost 
without cavity, and with a nearly smooth surface ; while in Cymbulia, on the contrary, we 
fi nd a fin with a ventral lobe, a short proboscis, not at all free, and a thick “shell” with 
a marked cavity and with a spiny surface. Thus we understand how the differentiating 
characters of the two genera are given with so much definiteness by the authors 1 who 
establish their generic diagnosis according to these two forms. 
o o o 
But these two forms ( Cymbulia peroni and Gleba cordata) are precisely the two 
extremes of the series of Cymbuliidse, and if we turn from these to the four other forms 
already enumerated, we find : — 
1. In Tiedemcinnia chrysosticta and in Corolla spectabilis, which belong to the 
genus Gleba, the proboscis is very short, as is also the case in a form from the Atlantic, 
figured by Boas (pi. iii. fig. 31, Spolia atlantica). 
2. In “ Cymbulia ” ovata and in “ Cymbulia” calceola, the fin presents a continuous 
margin and no ventral lobe. In these respects they thus resemble Gleba, while the 
proboscis, which is indeed short, is free, and resembles that of Tiedemannia chrysosticta 
and Corolla spectabilis. The “ shell,” on the other hand, is altogether different, both 
from that of Cymbulia and that of Gleba, for it is rather thin, with a tuberculated 
surface, and with a very large cavity. 
J. D. Macdonald also figures 2 a Cymbulia from the Indian Ocean without a ventral 
lobe to the fin. I have unfortunately been unable to see his specimens, but I entertain 
much doubt as to the form of this fin, since the “ shell ” of this form is very like that 
of Cymbulia peroni from the Mediterranean, and the latter, like one of the Challenger 
forms from the Western Pacific, exhibits a well-developed ventral lobe on the fin. 
On the other hand, “ Cymbulia ” calceola and “ Cymbulia ” ovata, which are entirely 
destitute of the above lobe, agreeing in this particular with the Cymbulia of Macdonald, 
possess a shell quite different from Cymbulia peroni, the Cymbulia figured by Macdonald, 
and Cymbulia parvidentata, n. sp., from New Zealand. This shell is not pointed 
dorsally, and does not exhibit ventrally the special truncation seen in the three forms 
above mentioned. It has a distinct slipper-like form, with thin w r alls, with a deep cavity, 
and without spines along its aperture. 
Prom the above it must be evident that the genera Cymbulia and Gleba are nearer 
one another than might be inferred from the contrast between Cymbulia peroni and 
Gleba cordata. It also becomes obvious that it is impossible to refer to these two 
genera alone all the forms which have been referred to the family Cymbuliidse. 
“ Cymbulia ” ovata and “ Cymbulia ” calceola cannot be placed within either genus, 
1 See Gegenbaur, Untersuchungen fiber Pteropoden und Heteropoden, p. 40, note 1. 
2 On the General Characters of the genus Cymbulia, Proc. Boy. Soc., vol. xxxviii. p. 252. 
