102 
THE VOYAGE OE H.M.S. CHALLENGER. 
that the aperture occupies the entire length of the shell. There is a second nuchal 
portion of the same nature (at least in Gleba cordata = Tiedemannia neapolitana). 
Animal with a cephalic portion (“ trompe ”) more or less elongated, free over its 
entire length, situated in front of the fin, and enlarged towards its distal extremity. 
Near this the fin forms a disc, with continuous margin, and 
without ventral lobe. No radula or jaws. 
The shell of this genus was observed for the first time by 
Fl shen7f S &ve6a; thfdotted line Krohn 1 in Gleba cordata. It falls off so readily that specimens 
indicates the aperture. without their shells are very frequent, and it is difficult to 
preserve a specimen intact, with the shell in its natural position. This fact explains how 
the older authorities (Forskal, van Beneden, Delle Chiaje, &c.) did not observe the shell of 
Gleba cordata, and have even described other species as naked. 
There is certain evidence of the presence of this genus in almost all the seas. 
Unfortunately, a large proportion of the available material consists of incomplete or ill- 
preserved specimens, while many of the forms noted are only known in their young and 
immature stages. 
The number of species known in their adult state is really only three : — Gleba 
cordata, Forsk&l, “ Tiedemannia ” chrysosticta, Gegenbaur, “ Corolla ” spectabilis, Dali, 
and of these the last two have not yet been figured. 
Key to the Species. 
I. Proboscis long, ......... Gleba cordata. 
II. Proboscis short. 
1. Gilded spots on tbe fin, ...... Gleba chrysosticta. 
2. Fins of an uniform colour, ....... Gleba spectabilis. 
1. Gleba cordata, Forsk&l. 
1774. Gleba cordata, Forsk&l, leones rerum naturalium, pi. xliii. fig. d. 
1839. Tiedemannia napolitana, Delle Chiaje, in van Beneden, Exercices zootomiques, M4m. 
Acad. Sci. Bruxelles, t. xii. p. 22, pi. ii. fig. 1. 
1844. Cymbulia proboscidea, Krohn, TJeber eine neue Pteropoden Art, Archiv f. Naturgesch., 
1844, Bd. i. p. 327. 
1844. Tiedemannia creniptera, Krohn, Ibid., pi. ix. fig. a. 
1847. Tiedemannia neapolitana, Krohn, Nachtrage zu den Aufsatzen fiber Tiedemannia, &c., 
Archiv f. Naturgesch., 1837, Bd. i. pi. ii. figs, b, c. 
This species has been generally but poorly figured. The best drawings are 
those given by Krohn ( loc . cit .) and by Gegenbaur, 2 which supplement each other, 
1 Nachtrage zu den Aufsatzen fiber Tiedemannia, &c., Archiv f. Naturgesch., 1847, Bd. i. pi. ii. figs. B, c. 
2 Untersuchungen fiber Pteropoden und Heteropoden, pi. v. fig. 1. 
