30 DEEP SEA FISHES. 
bulbus. Figure 3 exhibits the internal arrangement of the intestine. The 
number of circuits in the spiral is small, only four or five, and a diagram- 
matic representation would somewhat resemble that of Chimaera monstrosa 
as given by T. J. Parker, 1879, in the Transactions of the Zoological Society 
of London, XI., Pl. IL, fig. 6. The peculiar structural arrangement of 
the papillose ridges of the absorbing surfaces of the membranes within the 
intestine of Centroscyllium mgrum is to be seen on Plate V., fig. 3 of the 
present work. The cecal appendage of the intestine is elongate and 
subcylindrical. 
On the skin the scales are more or less distant from one another; they 
are small harsh tubercular spines, each of which has an erect or hooked 
slender grooved cusp, and a comparatively broad stellate base, Plate IV., 
fig. 7. The lateral system is rather simple; the arrangement of the canals 
on the head does not differ greatly from that of Iswrus punctatus (Garman, 
1888, Bull. Mus. Comp. Zool., XVII., Lat. Syst., Plate I.) or from that. of 
Isistius brasiliensis, Plate LXIX,. fig. 2 of the present work, except perhaps 
in that the halves of the aural canal do not meet in the middle. This 
separation of the part of a canal on one side from the part on the other 
side of the head is noted in widely different genera, for instance on Hepta- 
branchias maculatus, Lat. Syst., Pl. XIV., fig. 2, or particular canals on one 
or on both sides of the head may be similarly interrupted, as on Somniosus 
carcharias, Lat. Syst., Pl. XX., fig. 1, where cranials, orbitals, and occipitals 
are disunited. What credit for such breaks in canals ordinarily continu- 
ous may be given to individual variation is only to be determined by 
examination of a number of specimens of whatever species may be under 
consideration. 
The fins are of medium size; the amount of fin area is much the same 
in dorsals, pectorals, and ventrals. The first dorsal originates very little 
backward of a vertical from the axil of the pectoral; the spine is triangular 
in cross section, concave or grooved on each side, and is shorter and more 
erect than that of the second dorsal. The origin of the second dorsal is 
little, if any, backward of the middle of the bases of the ventrals; the spine 
is about one and one-half times as long as the anterior spine, and is similar 
in structure but more hooked. On the tail the upper lobe of the caudal 
is separated from the lower by a distinct notch and is subtruncate on the 
hind margin ; the lower lobe is the deeper, and has its lower angle slightly 
a ee 
