284 
S LADEN : STEUCTURE OF ASTEROIDEA. 
I. Lateral plates. These plates usually bear spines, which have 
been omitted from the diagram. 
p. Paxilke of the dorsal area. 
t Ambulacral tentacle or sucker-foot. 
Fig. 2. — Section through the ray of an Ophiuroid (Opluarachna ), at 
the junction of two segments. Magnified and partly diagrammatic. 
a. Disk of the axial skeleton of the segment. 
b. Side arm-plate. This plate bears the arm-spines, which have 
been omitted from the diagram for the sake of clearness. 
c. Upper arm-plate. 
d. Under arm-plate. 
t. Ambulacral tentacle. 
Fig, 3. — Section through the ray of Astrophiura, at the junction of 
two segments. Magnified. 
Same letters as above. 
In each of the figures homologous parts are marked with the same 
letters. 
The Water- vascular system is coloured blue, and the position of the 
Nervous system is indicated in red. 
ON THE GEOLOGY OF THE DISTRICT OF AROUND MIDDLES- 
BOROUGH. BY W. Y. VEITCH. (ABSTRACT.) 
This Paper was of the utmost service to the members who attended the meeting at 
Middlesborough, and contains a clear account of the Geology ; with remarks on the Flora of 
the District. There is howevernot sufficient new matter to render its publication necessary. 
THE town rests upon an estuarine deposit consisting- of clay, sand 
and gravel, with patches of a peaty nature distributed in low- 
lyings places, containing much vegetable remains, large trunks 
of oak, a few antlers of the red deer, and numerous shells of 
the Scrobicularia piperita. 
A staple going 27ft. below low- water mark, at the new gas 
tank, revealed nothing but layers of soft blue clay mixed with 
vegetable matter, and a loamy mixture of silt clay and vegetable 
matter. Below this is the new red sandstone containing enormous 
deposits of salt, upwards of 100ft. in thickness, at a depth of about 
400 yds. At high water the low-lying places referred to are 
saturated subterraneously with water, which again disappears 
with the receding tide. 
