656 R. C. PUNNETT. 
whilst the cesophagus at this level is very small. The genital pleurae are still large in this 
region but become much reduced shortly after it. 
Ptychodera viridis, n. sp. (Pl. XXXVII. figs. 2, 6, 7; Pl. XXXIX. fig. 32; Pl. XLII. 
figs. 17 and 19). 
Locatity, ETc. From Hulule, Maldive Is. Three specimens only, two being complete, 
were dug from sand towards the cast of the island. 
EXTERNAL FEATURES. Coloured sketches from life of this worm were fortunately made 
by Mr Forster Cooper. From the reproductions of these on Plate XXXVII. it will be seen 
that green is the prevailing tint on the body of the animal, though the proboscis is pale 
yellow, and the collar pale yellow with a certain amount of orange. To the predominant 
body tint the animal owes its specific name. From the sketches it appears that the proboscis 
is considerably longer than the collar, a proportion which still exists in the preserved creature. 
The length is not great. Of the two complete specimens one measured 36 mm. and the 
second only 21 mm. in length after preservation (ratio of total length to collar length being 
respectively 18:1 and 14:1). Compared therefore with such forms as Pé. flava, var. lacca- 
divensis, this species is a small, short, and somewhat stunted form. The genital pleurae 
are well-developed. The external liver saccules are relatively feebly developed and are of 
a uniform colour. 
INTERNAL STRUCTURE. The musculature of the proboscis is strong and compact, the 
radial bundles into which the longitudinal muscles are gathered being closely connected by 
connective tissue. The powerful development of the longitudinal muscles leads to the practical 
obliteration of the proboscis cavity (Pl. XXXIX. fig. 32). A well-marked dorsal muscular 
decussation occurs in the anterior part of the proboscis (Pl. XX XIX. fig. 32, dd) and 
fibres from it pass ventral to the central complex. Dorso-ventral muscles anterior to the 
pericardium are not present. The ventral proboscis septum reaches forwards almost to the 
tip of the stomochord. The racemose organ is small and unlobulated. Both proboscis pores 
are present though only one is in functional communication with the dorsal proboscis coelom. 
This may be either the right or the left one. 
Collar. The musculature and the connective tissue are here strongly developed and 
the cavity of the collar is very much reduced. The dorsal septum occurs after the first 
root as usual and is generally complete. Traces of the ventral septum may occur. The 
lumen of the collar cord is almost entirely obliterated throughout and the cord in section 
has as great a dorso-ventral diameter as a lateral one (PI. XLII. fig. 19). In one of the 
specimens sectioned three roots were present of which the last was rudimentary. 
The cornua of the nuchal skeleton apparently vary much in length. In one specimen 
they extended over about } of the collar, whilst in another they were rather more than a 
quarter as long as this structure. 
Trunk. The branchial region is short. Compared to the collar length as unity it 
measured in the three available specimens ‘85, 1:00, and 1°44, giving an average of 1:10. 
The branchial portion of the cesophagus is approximately of the same size as the ventral 
portion. The post-branchial groove is very short and insignificant. The genital folds are 
large in the branchial region and also in the region of the post-branchial groove (Pl. XLIL 
fig. 17). 
