ZOOLOGICAL OBSERVATIONS IN THE SOUTH PACIFIC. 231 
EXPLANATION OF PLATE 13, 
Illustrating Dr. Willey’s “ Zoological Observations.” 
Figs. 1—4 refer to Asymmetron caudatum, n. sp. See p. 219. 
Fic. 1.—Asymmetron caudatum, n. sp. Posterior extremity of 
female from right side. d. Dorsal. v. Ventral. From living object. 
Fic. 2.—A. caudafum. Anterior extremity of female from right side. 
From living object. 
Fic. 3.—A. caudatum. Posterior extremity of male from right side. 
From living object. : 
Fie. 4. A. caudatum. Anterior extremity of male from left side. 
From living object. 
Fig. 5.—N. umbilicatus. Drawing of umbilical region to show the 
nepionic line, which is situated a little beyond the first complete whorl of the 
shell. From right side. 
Fic. 6.—N. pompilius. Outline sketch of young shell with perforated 
umbilicus, to show nepionic line. From right side. 
Fic. 7.—N. pompilius, v. perforatus, nov. var. Umbilicus partially 
perforated. The dotted line is merely to indicate the limit of the black 
pigment on the anterior convexity of the shell. Right side. 
Fic. 8.—N. pompilius, v. marginalis, nov. var. Umbilical region of 
left side, to show the umbilical shoulder and depression. 
Vie. 9.—N. pompilius, v. Moretoni, nov. var. Umbilicalregion, showing 
shoulder, perforation, and whorls. From right side. 
N.B.—The drawings are placed in such a way that the convex surface of 
the shell would be directed upwards and the mouth of shell downwards, 
because it is thought that they would be more intelligible in this position ; 
but the right and left sides are named with the shell considered in the 
natural position, with the convex surface directed downwards and the month 
upwards. 
