REPORT ON THE PTEROPODA. 
45 
Bcdantium recurvum, Benson, . 
Creseis spinifera, Bang, 
Cleodora striata, Delle Chiaje, . 
Hyalsea tricuspidata, Bowdicli, 
Creseis unguis, Eschscholtz, 
Styliola vitrea, Terrill, 
Creseis zonata, Delle Chiaje, 
The genus Clio thus includes fourteen 
among the spoils of the Challenger. 
Creseis virgula, Bang. 
Creseis acicula, Bang. 
Creseis conica , Eschscholtz. 
Cleodora chierchiae, Boas. 
Creseis striata, Bang. 
Cleodora subula, Quoy and Gaimard. 
Hyalsea i australis, d’Orbigny. 
= Cleodora balantium, Bang. 
= Cleodora subula, Quoy and Gaimard. 
= Creseis conica, Eschscholtz. 
= Hyalsea cuspidata, Bose. 
= Creseis virgula, Bang. 
= Creseis conica, Eschscholtz. 
= Creseis striata, Bang. 
real species, of which eleven are included 
Cleodora sulcata, Pfeffer. 
Cleodora chaptalii, Souleyet. 
Cleodora bcdantium, Bang. 
Bcdantium politum, Craven, MS. 
Cleodora andrese, Boas. 
Clio pyramidata, Linne . 1 
Hyalsea cuspidata, Bose. 
This genus is thus the richest of the Thecosomata, and indeed of the entire group 
of Pteropods. It is also that which exhibits the greatest variety of forms. It may 
w r ell be asked whether all the species should be ranged in uniform succession in a 
homogeneous series, or whether further classification is not possible. 
Bang, Philippi, Souleyet, Gould, Pfeffer, Boas, &e., are of opinion that all the 
species ought to bear the same generic title, and the anatomical researches of Souleyet 
have shown that the structure is nearly the same in the different forms examined. 
On the other hand, the conchologists who are never afraid of a multiplied of 
names generally divide into three or four genera the series of forms which we comprise 
under the title Clio. 
But the attempt towards classification most worthy of attention is certainly that of 
Fol , 2 who bases his arrangement on the ontogenetic development of Mediterranean forms. 
Fol divides the living species of Clio into the four following genera : — 
Hyalocylis, Fol ; type Creseis striata, Bang. 
Styliola, Lesueur ; type Cleodora subula, Quoy and Gaimard. 
Cleodora, Peron and Lesueur ; type Clio pyramidata, Linne. 
Creseis, Bang ; type Creseis acicula, Bang. 
1 Cleodora occulentalis, Dali, appears to be nearly related to Clio pyramidata. From an unpublished figure which 
Mr. Dali has been good enough to send me, it possesses between each fin and the posterior lobe of the foot a conical 
tentacle, which is not found in Clio pyramidata ; but as I have not been able to examine specimens of “ Cleodora occi- 
dentalis ” I cannot give a decided opinion on this question. 
2 Sur le d6veloppement des Mollusques Pteropodes, Archives d. Zool. Expdr., ser. 1, t. iv. pp. 177, 178. 
