REPOET ON THE NTTDIBR AN CHIATA. 
61 
little excavated in the direction of the long axis ; the free inner side is perfectly smooth 
under the microscope, and is somewhat concave in height and length, especially in the 
hinder half, from which the anterior half stands off like a special facette. More minute 
investigation showed the plates to be of a dense and finely striated structure, in which, 
however, there was no trace of any rods (as in Euplocamus croceus and japonicus 1 ). 
The tongue is very large, somewhat flattened, covered as far as the radula with a 
thick, tough, whitish cuticle ; the cleft is deep, rather wide, and covered at its sides by 
the yellowish radula, and closed behind by the keel-shaped projecting lingula. The 
structure of the organ appeared to agree with that of Euplocamus croceus . 2 The rhachis 
of the radula was divided into areas by furrows (fig. 13), and with strong arches formed 
of closely -pressed furrows lying behind each other, and separated by intervals. At the 
point of the tongue there were several similar arches and furrows, which appeared to 
indicate that several rows of teeth had formerly been present, but were now rubbed off'. 
The radula had ten or eleven rows of teeth, but further back, within the radula-sheath, 
there were but three fully developed and two undeveloped series ; the total number w T as 
thus about sixteen The first two or three-row's were incomplete, and the large teeth upon 
them were evidently worn. Each row had two large lateral (fig. 13, a b), and, at any rate 
in the young series, six external teeth (fig. 13, cc). The lateral plates were rather like 
each other, the innermost (figs. 13, aa, 14, a, 15, a) somewhat smaller than the outer ones 
(figs. 13, bb, 14, b, 15, bb). The basal portion of these lateral plates is flattened and 
obliquely truncate behind ; from the outer margin arises obliquely a strong com- 
pressed crest, rounded above ; in front the basal portion is continued into the 
incurved hook, the apex of which is rather flat (figs. 13, 14). The outer row of 
teeth joins the hinder half of the base of the second lateral plate (fig. 13, cc). There 
were five of these external teeth in the middle of the tongue and six elsewhere. The 
innermost of these (figs. 16, 18, aa) has just a trace of the terminal hook, and is 
larger than the others, which otherwise resemble each other ; they are longish, a little 
depressed, but hardly perceptibly broader than high ; the under surface is narrower than 
the upper, which slopes outwards, the inner margin being more bulged forward (figs 
16-18). The teeth were all yellowish, the large side plates rather darker in their thicker 
portions. The length of the inner lateral plates (on the root of the tongue) was about *5 mm. , 
their height about ‘3 mm.; the outer lateral plates usually '6 mm. in length by '4 mm. in 
height ; the length of the innermost outer tooth was '28 mm. in length and '08 in height ; 
the succeeding one measured '22 mm. in length, the third *2, the fourth *18, the fifth 
*16, and the sixth *14 mm. The tissue of the radula-pulp contained a number of large 
odontogenous cells behind the younger series of teeth. 
The salivary glands were smaller, and did not extend so far back as in Euplocamus 
croceus ; 3 they were yellowish-white in colour ; the efferent ducts rather short. 
1 Bergh, loc. cit., Taf. xi. fig. 12 ; Taf. xii. fig. 14. 
3 Cf. Bergh, loc. cit., p. 632. 
2 Loc. cit., p. 630. 
