88 
THE YOYAGE OF H.M.S. CHALLENGER. 
Challenger Specimens. — I. Living specimens. 
Between Stations 162 and 163, April 3, 1874; Melbourne to Sydney; lat. 38° 7' S., 
long. 149° 18' E. 
Station 181, August 25, 1874; Sydney to Raine Island; lat. 13° 50' S., 
long. 151° 49' E. 
Between Stations 247 and 248, July 4, 1875; Yokohama to Sandwich Islands; 
lat. 36° 42' N., long. 179° 50' W. 
II. Deposit shells. 
Station 219, March 10, 1875 ; Admiralty Islands to Yokohama; lat. 1° 54' 0" S., 
long. 146° 39' 40" E.; depth, 150 fathoms; bottom, coral mud. 
2. Cleodora pyymsea, Boas. 
1886. Cleodora pygmxa, Boas, Spolia atlantica, p. 84, pi iv. fig. 57. 
The close resemblance which this form presents to Cleodora compressa shows that it 
must be the young stage of a species nearly allied to Cavolinia trispinosa. But the only 
species very nearly related to the latter is Cavolinia quadridentata. 
In the last mentioned, as in Cavolinia longirostris, the initial portion of the adult 
shell is caducous, and is as yet quite unknown, so that Cleodora pygmsea fills up a 
blank. 
The three dorsal ribs of Cleodora pygmsea correspond absolutely to those of Cavolinia 
quadridentata. The latter is more globular than Cavolinia trispinosa; Cleodora 
pygmsea is also less flattened than Cleodora compressa. Finally, the geographical 
distribution of the two forms is virtually the same ; Cleodora pygmsea has only been 
found in localities where Cavolinia quadridentata also occurred, in the Indian and 
Pacific Oceans. 
3. Cleodora curvata,. Souleyet. 
1850. Clio pellucida, Gray {pars), Catalogue of the Mollusca in the Collection of the British 
Museum, pt. ii., Pteropoda, p. 14. 
1852. Cleodora curvata, Souleyet, Yoyage de la Bonite, Zoologie, t. ii. p. 185, pi. vii. figs. 6-10. 
Boas, following Souleyet, regards this form as a species of Clio {Cleodora), and denies 
that it is only a young stage. 1 Nevertheless it must be noted (1) that the figure of 
Souleyet shows that the genital organs are scarcely developed, a good proof that the 
form is not adult, and (2) that the absence of a marked constriction limiting the 
embryonic shell shows that the form in question is a Cavolinia and not a Clio. Krohn 2 
has already identified it as a young Cavolinia. 
1 Spolia atlantica, p. 81. 
2 Beitrage zur Entwickelungsgeschichte der Pteropoden und Heteropoden, p. 43. 
