EXPI.ANATION OF PLATE IV. 1 



Fig. I. — Scalpellum squamuliferum, Welt. Pupa of hermaphrodite, x loo. ^ 



Minute valves were present, but are not shown. j 



,, 2. — 5. squamuliferum. Young hermaphrodite measuring 2-5 mm. in 



length, X 75. Decalcified and stained with borax carmine. The , 



testes, which are small at this stage, are not shown in the figure. 



,, 3. — S. squamuliferum. Transverse section through the capitulum of a 

 young hermaphrodite, x 180. 



,, 4. — S. squamuliferum. Pupa of male, x no. Stained borax carmine. 

 Erratum— the letters e.g. point to a vesicular space instead of to the 

 cement glands. The latter are represented by the group of small 

 sharp nuclei lying somewhat more ventrally. 



,, 5-— 5. squamuliferum. Pupa of male, showing valves. Unstained. ; 



,, 6. — 5. squamuliferum. Young male shortly after casting off the bivalve 



shell. Decalcified, unstained. j 



,, 7. — I bla cumingii, Darwin. Male, x 75. Stained borax carmine. j 



