SPECIAL DISCUSSIONS AND DESCRIPTIONS. 
HOLOCEPHALA. 
Aolocephala Miiller, 1835, Vergleichende Anatomie der Myxinoiden, 10. 
Of the occurrence of species belonging to this group in the region 
traversed by the expedition there can be little doubt; they occur at a 
comparatively short distance to the north and to the south, yet the 
absence of representatives in the material under examination limits the 
‘discussion in these pages to matters pertaining to the group in general 
as inhabitants of great depths. 
One species of the genus Chimaera Linné, 1758, C. monstrosa L., has 
been noted by Vaillant, 1888, from a depth of 687 fathoms, off the Azores, 
and another species, C. afinis Capello, more often taken at great depths on 
both sides of the north Atlantic, is given by Giinther, 1887, a range from 
200 to 1200 fathoms, or by Vaillant to J285. An ege referred to C. 
monstrosa by Alcock, 1892, from a depth of 410 fathoms, off the Coroman- 
del Coast, probably belongs to a new species. Climaera Collie Lay and 
Bennett, 1859, is a shoal water fish that descends to depths of a hundred 
fathoms or more at particular seasons, off the coast of California. By 
some mistake the figure of this fish in the Zoology of Beechey’s Voyage, 
Fishes, Plate XXIII., fig. 1, has been copied in the ‘“ Oceanic Ichthyology,” 
Plate X., fig. 36 as “ Callorhynchus antarcticus.’ So far as now known, the 
species of Callorhynchus have habits similar to those of Chimaera Collie’; 
though the specimens secured have been taken at moderate depths, the 
species in all likelihood retreats at certain times to greater depths, as is 
the case with most Selachians and Fishes. It will be evident on compari- 
son with the egg figured below, Plate LXIV., fig. 2, as that of Cadlorhynchus 
antarcticus, that Giinther is probably correct in identifying the egg figured 
by J. Miiller, 1842, Ueb. den Glatten Hai, Taf. 6, fig. 3, and that figured 
by Duméril, 1865, Poiss., I., Pl. 8, fig. 8, as eggs of Callorhynchus, the 
