Manchester Memoirs, Vol. xlvi. (1902), No. 10. 7 



chiti'n or some similar substance of horny consistency, 

 which may have been deposited around such a centre, 

 which would, in this view, be comparable to the minute 

 central cavity seen in the spicules of sponges. In a great 

 many instances these bodies are split and cracked as hard 

 substances might do under the pressure of the razor. 

 The interspaces between these scales are occupied by a 

 delicate connective tissue, which is continuous externally 

 with the inner layer of the external capsule. Here and 

 there the scales are so arranged as to leave passages by 

 which nerve fibres reach the central mass {Figs. 3 and 4, n). 



3. The inner cup {Fig. 3, i.e.) has really the shape of 

 a funnel with an aperture at the bottom through which 

 projects the central knob of the central mass. The funnel 

 is much thickened at the rim and thins away towards the 

 central aperture. The diameter of the funnel is about 

 07 mm. in the largest organs, the depth 0-3 mm., the 

 thickness of the rim O'l mm., and the diameter of the 

 aperture at the bottom about O' 15 mm. It is composed 

 of wavy fibres, which stain rather deeply and are dis- 

 posed for the most part parallel to the inner surface of 

 the funnel. 



4. The central mass is divisible into two portions, (A) 

 a spheroidal knob, which occupies the centre of the 

 organ (Fig. 3, s.k), and (B) a conical projection arising 

 from its anterior surface (Fig. 3, c.p.) 



(A) The central knob is spheroidal, about o'i5 mm. in 

 diameter, and occupies the hollow space enclosed by the 

 posterior cup above mentioned. It stains but very faintly, 

 and is of a finely granular texture ; a few nuclei are 

 scattered in it here and there and are most numerous 

 near the outer surface. The mass of this body is seen 

 to be divided up by a number of fine lines, rather more 

 deeply stained than the general mass, into a number of 



