292 Transactions. — Zoology. 



Plate XXV. 



Lamontia zona. 

 Fig. 1. The sponge, natural size. 

 Fig. 2. Portion of pore-area, from below. 

 Fig. 3. A pore, with muscle (?) cells. 



Fig. 4. Portion of base of peristome, with cells of sphincter. 

 Fjg. 5. Section through pore-area: ch., chone ; s.c. subcortical crypt ; 



col., column of 3-radiates. 

 Fig. 6. Longitudinal section : ex., exhalent canals. 

 Fig. 7. „ s.L, subcortical lacuna. 



Fig. 8. Prosopyle and collared cells. 



Plate XXVI. 



Lamontia zona. 



Fig. 1. Parenchymal oxea. 

 Fig. 2. Large oxea of dermal cortex. 

 Fig. 3. Spined oxy-strongyla of dermal cortex. 

 Fig. 4. Oxea of peristome. 

 Fig. 5. a-c, 3-radiates from base of peristome. 

 Fig. 6. a-d, 3-radiates of dermal cortex. 

 Fig. 7. a-f, 4-radiates from neighbourhood of oscule. 

 Fig. 8. a, three "dagger" spicules from gastral surfaoe. 

 b, „ „ in situ. 



Art. XXXV. — On a Netv Shell (Anomia walteri). 



By Sir James Hector. 



[Read before the Wellington Philosophical Society, 20th February, 1895.] 



Shell fragile, nacreous, with brilliant lustre and translucent. 

 Form irregular, the upper valve convex, corrugated, and often 

 bullate. Structure lamellar, with faintly-marked wide ribs 

 and wavy rays. On the interior surface a triangular area of 

 white shell extends from the cartilage-pit to the middle of the 

 valve, within which area are three distinct and equal-sized 

 muscular scars. The cartilage-pit is single and straight, sub- 

 marginal, and under a feebly-developed beak. The lower 

 valve is horny and almost transparent, except an opaque white 

 crescent round the notch. In form it is concave, and imbedded 

 in the upper valve like an operculum. The notch is of. a 

 moderate size, with a strong anterior process which is hinged 

 to the pit in the upper valve by a black ligament. The pos- 

 terior margin is very thin. The shelly plug has not been 

 preserved in any of the specimens. Colour : Upper valve 

 rich honey-yellow, sometimes with pink tint ; lower valve 

 colourless. 



