CEPHALOPODA (tetrabeanchiata), pteropoda. MolL 43 
the weblike arms in Argonauta. J. de Conch, xxviii. pp. 355-362, with 
woodcut. 
H. V. Ihering agrees with Barrande that the Ammonitidce, must have 
been Dibranchiata, not Tetrabranchiata, not only because their embryonal 
shell is more like that of Spirula and Belemnites, but also because the 
Aptychus corresponds to the nuchal cartilage of the Dibranchiata , Z. wiss. 
Zool. XXXV. p. 18. 
PTEROPODA. 
G. Pfepfer reviews, from a comparative morphological point of view 
the different forms of the shell in the Hyalceidce. He states that, in 
Diacria, Cleodora, Balaniium, Triptera, and Creseis (but not in Hyalma 
proper), a limited enlbryonal part of the shell is to be distinguished, 
which is either preserved or lost in the adult. He also points out the 
differences between young and adult forms of the same species, the per- 
sistence of juvenile characters in some full grown varieties, and the 
mechanical loss of certain parts of the shell, namely, the lateral points 
and the upper lip, which occurs almost regularly in some species ; and he 
mentions some interesting instances of external resemblance in colour and 
shape between distinct species collected at the same spot. Abh. Ver. 
Hamb. vii. pp. 70-77. 
The same author arranges the HyalmdcB in the following groups, but 
does not assign them to distinct genera, because an anatomical com- 
parison of them has not yet been made : — 
tridentata (Forsk.) = and cumingi (Sow., Reeve), and affinis 
(Orb.) = truncata (Krauss) = forskali (Rang) = tridentata var. 
(Sow., Reeve), pp. 77-82, pi. vii. figs. 1 & 2. 
uncinata (Rang) and uncinatiformis^ n^w form, Atlantic, pp. 82 & 83, 
figs. 3 cr. & b. 
globulosa (Rang), p. 83, fig. 4. 
gibbosa (Rang) = flava (Orb.), and gegenbauri^ new form, = gibbosa 
(Orb., nec Rang), pp. 84-87, figs. 5-7. 
longh'ostris (Les.), p. 88, figs. 8a & b. 
labiata (Orb.), p. 89, fig. 10. 
injlexa (Les.) and imitans, new form, from Zanzibar, pp. 89 & 90, 
figs. ^ a & b. 
quadridentata (Les.) and costata (Pfeffer, 1879), pp. 90 & 91, figs. 11 
& 12 . 
trispinosa (Les.) and mucronata (Q. & G.), p. 92, figs. 14 & 15. 
laevigata (Orb.) and longijilis (Troschel), p. 93. 
cuspidata (Q. & G.), p. 93. 
pyrarnidata (P6r. & Les.), martcnsi^ new form from the Atlantic and 
West Indies, sulcata (Pfeffer, 1879), and australis (Orb.), pp. 
93-95, figs. 15-18. 
balantium (Rang), p. 96, fig. 20. 
falcatum^ new group, near the preceding, but without sculpture, 
Atlantic, p. 96, fig. 19. 
striata (Rang), p. 96. 
1880. [vOL. XVII.] 
B 11 
