ZOOLOGICAL OBSERVATIONS IN THE SOUTH PACIFIC, 229 
lian Museum only a portion of the coil was dimly visible, and 
the free margin of the shell passed directly into the anterior 
border of the umbilicus without a prominent shoulder.! 
In Pl. 13, fig. 8, an interesting variation is shown in which 
the umbilicus was imperforate, yet nevertheless the free margin 
of the shell did not pass simply into the umbilicus, but bent 
round in such a manner as to form a prominent shoulder, 
behind which there was a deep umbilical depression. I have 
two examples of this variation from New Guinea, and in both 
cases the above-described shoulder was confined to the left side 
of the shell, the right side being normal. 
It will be found convenient to name these varieties. That 
first described above, with partially perforated umbilicus, may 
be called N. pompilius, var. perforatus, nov. var. 
The second variety, with the shoulder, may be called N. 
pompilius, v. marginalis, nov. var. 
Now we come to the third variety to be described, namely, 
N. pompilius, var. Moreton, nov. var. 
In this variety, which is a very well-marked one, there is a 
prominent shoulder as shown in Pl. 13, fig. 9; the umbilicus is 
somewhat widely perforated, and a considerable portion of the 
whorls can be distinctly seen. ‘This shell was symmetrical in 
every respect. At the first sight of it one might well hesitate 
whether to regard it as a loosely wound pompilius, or as a 
closely wound umbilicatus, but the existence of intermediate 
varieties shows, I think with certainty, that it belongs to the 
pompilius group. 
All the variations described above belong to the category of 
substantive variations, according to Bateson’s nomencla- 
* It may be added here that there also seems no reason for regarding 
N. scrobiculatus as other than a variety of N. umbilicatus. On this 
view the species of recent Nautilus would be reduced to three,—N. pom- 
pilius, N. umbilicatus, and N. macromphalus. 
2 All the varieties described in this paper were obtained in New Guinea, 
and with one exception from the natives. I have certain evidence of the 
living Nautilus occurring in New Guinea waters, but the natives know 
nothing of it, and it is not in a workable condition for the zoologist 
