REPORT OH THE NUDIBRAHCHIATA. 
25 
papillae are arranged in four groups on either side, but the arrangement is not so distinct 
as in other Nudibranchs. The first two groups are the largest and about equal in size ; 
the two others smaller but corresponding with each other in size. Each group is made 
up of a number of short transverse or oblique rows, occasionally horse-shoe-shaped 
(PI. XII. fig. 9, c) ; there are two to four, or sometimes as many as five or six, papillae 
in each row. Altogether the first group contained about thirty papillae, the second 
thirty to thirty-five, the third twenty-one to twenty-five, the fourth eighteen to twenty. 
The papillae are conical in form, somewhat constricted at the base, and firmly attached to 
the skin ; those on the outer side were nearly always much smaller than those on the 
inner side. The anal papilla is rather prominent (PI. XII. fig. 9, a), and is situated on 
the right side of the body, on a level with the anterior end of the second group of 
papillae. In front of it is the small triangular renal pore (fig. 9, b). 
The central nervous system consists of a pair of somewhat flattened oval cerebro- 
pleural ganglia ; the pedal ganglia are of about the same size as the cerebro-pleural ; 
the subcerebro-pedal commissure is about equal in length to the longest diameter of one of 
the pedal ganglia ; the visceral commissure is of about the same length. The olfactory 
ganglia at the root of the rhinophoria are rounded in shape ; the oval buccal ganglia are 
of about equal size with the olfactory, the commissure uniting the two buccal ganglia is about 
as large as the ganglion itself ; the gastro-oesophageal ganglia are provided with a short 
stalk, they are round in shape and contain one very large and several smaller cells, their 
size being about one-third of the buccal. The eye has a short stalk, the lens is yellowish, 
and the pigment deep black. The otocyst is a trifle larger than the eye, and has a very 
short stalk ; it contains a number of rounded and not very strongly calcified otoconia. 
The bulbus pharyngeus is strong and resembles that of the PEolidiadae proper ; it is 
about 4 mm. in length, 3 '5 mm. in breadth, and 3 '2 mm. in height ; the sheath of the radula 
projects backwards, the labial disk is typical. The mandibles are strong and convex, of 
a chitinous-yellow colour ; the hinge part is small, the simple crista connectiva narrow ; 
the masticatory process (PI. X. fig. 1 ) is short ; its edge is provided with several series 
of somewhat compressed rounded teeth ‘03 mm. in height (PI. XI. fig. 2). The accessory 
buccal cavities are rather large (PL X. fig. 1, c ). The tongue is strong and somewhat 
compressed, and has thirteen series of teeth ; further back within the radula sheath are 
six develoj>ed and two undeveloped series, the total number being thus twenty-one. 
The colour of the teeth is chestnut yellow, the height of the anterior ones is T mm., 
and passing backwards increases to about T4 mm.; the breadth of the youngest teeth is 
about ‘3 mm.; the form of the teeth (PI. XII. figs. 11-13) is somewhat clumsy; on each 
side of the pointed apex are from ten to twelve denticles, which are often hook-shaped. 
The salivary glands are rather small and elongated, whitish in colour ; the efferent ducts 
rather long. 
The cesophagus is short and rather narrow, its length is 5 '5 mm. The stomach 
(ZOOL. CHALL. EXP. PART XXVI. 1884.) Cc 4 
