50 
THE VOYAGE OF H.M.S. CHALLENGER. 
*2. Clio ( Creseis ) conica (Eschscholtz) (PL II. figs. 1, 2). 
1829. Creseis conica, Eschscholtz, Zoologischer Atlas, Heft iii. p. 17, pi. xv. fig. 3. 
1830. Creseis striata, Delle Chiaje, Memorie sulla storia e notomia degli animali senza vertebre, 
pi. lxxxii. fig. 12. 
1869. Creseis conica, A. Costa, Pteropodi del golfo di Napoli, Rendiconto d. reale Accad. d. 
Sci. Napoli, 1869, p. 58. 
1872. (?) Styliola vitrea, Verrill, Recent Additions to the Molluscan Fauna of New England 
and the adjacent waters, &c., Amer. Journ. Sci. and Arts, vol. iii. 
p. 284, pi. vi. fig. 7. 
1873. Creseis conoidea, A. Costa, Pteropodi della Fauna del Regno di Napoli, p. 17, pi. iv. 
fig. 6. 
Characters and Description. — Shell conical, moderately elongated ; smooth over its 
entire surface ; a very slight and regular dorsal curvature ; the transverse diameter 
increasing gently and uniformly ; the posterior extremity of a dark brown colour ; the 
embryonic portion separated by a well-marked constriction, and thinning off towards 
the somewhat slender apex (PI. II. fig. 2). 
Animal like that of Clio ( Creseis ) virgula, but distinguished at first sight by this 
marked feature that the mass formed by the stomach and liver is situated much further 
forward than in the above species. For while in Clio virgula the broad oesophagus is 
very long, and the mass in question removed from the posterior extremity of the shield 
(pallial gland) by more than the length of the latter, in Clio conica it is situated imme- 
diately behind the shield. With this difference there is obviously correlated the abrupt 
and precocious enlargement of the shell in Clio virgula, and the gentle uniform increase 
in Clio conica. 
Observations. — I. There can be no doubt in regard to the species figured by 
Eschscholtz. It is not Clio ( Creseis ) acicula, since it is much too short in proportion, and 
has its posterior extremity of a dark brown colour. It is not Clio ( Creseis ) virgula, 
since it exhibits neither the abrupt curvature nor the precocious enlargement of diameter 
exhibited by that form, and since the visceral mass is situated anteriorly. Neither is 
it Clio ( Styliola ) subula, although Gray 1 and Souleyet 2 so regard it. The absence of a 
dorsal groove, the colour of the posterior extremity, and the shortness of the posterior 
lobe of the foot are enough to show that it is not. 
The “ Creseis conica ” of Eschscholtz is in fact the species which one finds at Naples, 
and in all probability that which Delle Chiaje noted under the name of “ Creseis 
striata.” 
A. Costa, thinking he had discovered a new species, described this form as Creseis 
conica, ignoring the fact that this title had been already used by Eschscholtz. Becoming 
aware of this, but failing to recognise the identity of the two forms, he changed the name 
conica to conoidea. 
1 Catalogue of the Mollusca in the Collection of the British Museum, pt. ii., Pteropoda, p. 17. 
2 Histoire naturelle des Mollusques Pteropodes, p. 55. 
