486 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 11, 
EXPLANATION OF PLATES XXXI. & XXXII. 
Puare XXXI, 
Fig. 1. <Asaphus platycephalus, Stokes.—Underside, showing the legs: a 6, 
suture through the doublure ; c, ¢, cavities on each side of the hypostoma; 
d, d, tubercles on the pygidium ; ff, cephalic doublure ; /, Z, the two lobes 
of the hypostoma ; 7, position of the mouth; x, 2, , 2, joints in the legs. 
Fig. 2. Transverse ideal section through the thorax: a, 6, the doublure of the 
pleure ; p, position of the Panderian organ. ‘The dotted line from 0 to 4 
indicates the contour of the ventral surface. 
Fig. 3. Ideal section through the head, cutting off the points of the hypostoma, 
J, (, ina plane passing through the eyes: 1, 2, position-of the Ist and 2nd 
pairs of legs. 
Fig. 4. Section through the tail of a small specimen, showing the doublure, ff. 
Fig. 5. Three pleure restored, showing the position of the Panderian organ at 
p; a, 6, portion of the pleurse removed. 
Fig. 6. Supposed leg of Trilobite, figured by Hichwald: a, natural size; 0, 
enlarged. 
Prate XXXII. 
Fig. 1. Asaphus platycephalus—Side view of the specimen which shows the 
legs, somewhat restored. The dotted line, a , represents the position of 
the plane of the ventral surface nearly. 
Fig. 2. Dorsal view of the same; the dotted lines indicate the position of the 
hypostoma and legs. : 
Fig. 3. Calymene senaria.—Section through the axis of the thorax: a, junc- 
tion of head and tail; 6, back of the head; ¢ d, hypostoma ; e, end of the 
tail; f, a body showing structure. 
Fig. 4. A group of the small bodies in fig. 3, enlarged 8 diameters. 
Fig. 5. The organic body seen at fin fig. 4, enlarged 3 diameters. 
Discussion. 
Mr. Woopwarp had carefully examined Mr. Billings’s specimen, 
and agreed with him in considering that there was undoubted 
evidence of the presence of walking-appendages under the thorax. 
The presence of such hmbs might @ prior: have been expected ; and 
the nature of the test suggested that the Trilobites were walking 
rather than swimming forms of Isopods. The branchiz had pro- 
bably been under the telson ; and this would account for its large de- 
velopment. It was not more surprising to find highly organized 
Trilobites than it was to find such highly erganized crustaceans as 
Prterygotus, Hurypterus and Shimonia in the same beds. 
Prof. Rupert Jones, Principal Dawsox, and Sir Wu. Logan 
made some remarks, more especially on Protichnites and Cliimactich- 
nites—the latter having been explained as galleries of Trilobites, by 
Prof. Jones, when first exhibited in England. 
2. Norr on the Paupus and other Apprnpaces of Asapuus, from 
the Trenton Lruestonn, in the British Museum. By Henry 
Woopwarp, Esq., F.G.8., F.Z.8. 
Havine been requested by Sir William Logan to examine the Tri- 
lobite sent over by Mr. Billings from Montreal, I was led to com- 
pare it with certain specimens in the British-Museum collection, 
presented by Dr. J. J. Bigsby, 1°.R.S., some years since. 
