BY T. HARVEY JOHNSTON AND OTTO S. HIRSCHFELD. 69 
None were found to be entirely brown though that colour 
predominates in the thicker parts of the shell of all 
specimens and in preserved material tends to become 
dominant. Sometimes the colour is almost a pure pale 
green, but brown tints are visible in the central portion of 
the valves. Longitudinal lines and also lines of growth 
are readily seen in decalcified valves. 
Morse (p. 320) in speaking of L. anatina from Japanese 
waters mentioned that he found a proportion of the shells 
thickened, discoloured and eroded, forming a marked con- 
trast to other specimens, equally large, but with clear green 
shells, thinner in texture and more perfect in condition. 
He believed that the animals with rougher and thicker 
valves were probably a year or more older than the others. 
We found such eroded thicker shells amongst the rather 
chinner shelled forms. 
Our smallest specimens measure 10.5 by 5.0 mm. with 
a peduncle of 100 mm. long, the ratio of the length of the 
ventral valve to its breadth being 2.1; 13.5 by 6.4 mm. 
(ratio 2.11), peduncle 20 mm. ; 12 by 5.6 (ratio 2.14) ; 20.5 
by 10 (ratio 2.05), peduncle 35 mm. ; 21.0 by 10.8 (ratio 
almost 2); 23 by 11 (ratio 2.1). Many of the collected 
specimens measured about 41 mm. in length by 20.5 mm. 
in breadth (ratio 2.0). A few large forms with thickened 
shell and light coppery tint reminding one of L. murphiana, 
measured 50 by 24 mm. (ratio 2.08). Another with a typical 
greenish shell not specially thickened had the same measure- 
ments. Of the 45 adults measured, 29 were between 40 
and 50 millimetres in length, 35 were between 32 and 
48 mm. The majority were between 43 and 46 mm. 
Thirty-eight had a breadth ranging between 20 and 24 mm. 
We find that the ratio of length to breadth is a very useful 
character in distinguishing Lingulids, being, at least in 
some species, a comparatively constant feature. Out of 
the 45 specimens measured, in two cases it was 1.9 ; in 19, 
2.0°; 14, 2:1 ; 6) 2.2): 3, 2.3 7 while in one it was 2.4) The 
average was 2.08. In 33 the ratio was between 2.0 and 2.1. 
In the longest specimen it was 2.08. Even in all the young 
animals measured it was found to range between 2.0 and 
2.14. Owing to the horny nature of the edges, the sides of 
